French keyboard on a laptop with an English keyboard

Buy lots of overlays, they seem to last quite a while then show someone responsible how to put them on and provide a photu if where they should all go.

Make a fool proof guide.  In my experience with these eee pc's it's not worth spending the extra money on proper keyboards as the laptops won't last that long.

I went to a book shop a purchased letters which rub off.

The letters are on a clear plastic sheet.
You place the sheet over the keys are rub over the letter.
This sticks the letter to the key.
...and it won't run off easily.

I would always go for option 2, but it is expensive and lengthy process.Is there no way you can buy EeePC with french keyboard?

In your surcubstances option 3 is best.

It seems you don't trust the sticker because it peels off.
I agree--stickers suck.

Another solution is the plug-in keyboard. Lots of people sell these. If you are not seeing French ones, try a search engine or dealer in a french-speaking country, like ebay.fr. Unfortunately an add-on keyboard is as big as an eee pc, so now you have a two-part computer.

You might also try to get a french keyboard for the eee pc. Dealextreme.com is a Hong Kong dealer who sells replacement eee pc keyboards. The ones I saw there were English, but you could write to them and tell them you need 30 French eee pc keyboards. The size of your order may improve your chances of success. A Hong Kong dealer is perfectly situated to buy products cheap in the land where they are made.

You could also try to pry off the keys that are in different locations for the french language and replace them in the correct locations. eee pc has the number pad printed on  some alphabet keys so you may need to grind off the key printing that is wrong.

Finally, you could find a local artisan with an engraving tool or Dremel to etch the correct letters into the keytops and then fill them with acrylic enamel paint. Maybe let them show you the quality of their work on a broken keyboard before you give them your new eee pcs.

How about this idea:-

http://www.amazon.com/Universal-Silicone-Keyboard-Protector-Notebook/dp/B001A4B3W4

Speed of commissioning the keyboards is an issue, I would have thought.  If the protectors are see-through (and I think that means they give a slightly frosted effect, from the protectors I've seen), applying a Letraset legend on a key that needs it would override the legend on the underlying key.

You seem to be in a hurry but you don't trust any of the quick solutions. You don't explain why you bought EEE pcs with English keyboard and (presumably English XP Home for users in a french-spreaking country. I'm not sure if you are still looking for a solution but I'll amplify my assessment of your choices.
Quick:
1. Letraset was proposed. These are pressure-sensitive letters on a plastic sheet. You would need to buy these in the French language, I'm not sure if they are available locally where you are. (Letraset was pretty commonly used for preparing pasteups for offset printing before cheap printers became fully graphics-capable.) You would apply these one by one to the keys and then you would spray them with a clear varnish-type spray or paint. If you don't use the fixative they rub off very quickly. You could also apply these to an overlay. I don't think that is a good idea because you can't apply them to the bottom of the overlay, only the top, where they would also rub off quickly. Bad.
2, Stickers. Quick, but not permanent. Better than the ruboffs in #1 IMHO, but you have already rejected this option because they peel off.
3. Stickers on an overlay protector. You would need to clean the sticky part off the botton of the sticker so you could aply clue to the top and glu them to the bottom of the overlay. Then they would wear and would be protected from peeling off. Cons: PITA to get the glue off without dissolving the ink on the sticker.
4. Local artisan to engrave letters on the keyboards and fill with paint. This could be pretty quick if you have the local artisan available. The person to look for would have a local service doing detail painting, signmaking, window or metal etching, jewelry or engraving. If this skill doesn't exist in your area then you can't do it, but most areas have a jeweler or machinist who could do this. You don't need to do the entire keyboard, just a few letters on the number line. The other letters could probably be pulled off the keyboard and rearranged.
Pro: The lettering may last longer than the original letters. Locally done. Possibly could have them done the same day.
Con: The modified keys probably won't match exactly. (Depends on artisan skill.) Could be expensive if artisan senses your desperation.
5. Buy the eee pc replacement keys or keyboard. It will be a perfect fit and as good as new. This is the standard of 100% quality.

The engraver could come to 100% of quality depending on his skill. Stickers are about 50-70% of original quality. Letraset is 10-50% depending on skill of applyer.

How much time have you got left to consider any more ideas or workarounds?

Now I understand rfwoolf's reasons for rejecting my engraving suggestion, and since replacement keyboards for eee pc go for $15 to $35 I see the the upper side of his budget.  Really this is a problem with no nice solution. You can't make your own socks for the price you can buy them, even if you value your labor at zero and the same goes for keyboards.

The solution is going to involve some kind of replacement lettering on the existing keytops. If it is not a sticker then it needs to be paint. Letraset can look good if applied to a flat surface and protected with a clear overlay like varnish or a sticker. I've used Letraset a lot many years ago and I would hesitate trying it on a keytop. You still need to remove the old paint and you need to mask the letters to spray. Brushing on a clear varnish is ok but requires experimentation to make sure it doesn't crack the letters or dissolve something. Overall a PITA.

The overlay idea is risky, if you are in a hurry. I've ordered from DealExtreme and got their free shipping. They have been pretty reliable but can be slooooow. They may offer expedited freight at higher cost, but they are a small company and may or may not be able to accommodate a rush order for 30 overlay sheets. The overlays cost $8 with free shipping.

Can you get language sticker sheets locally? I know Amazon has language keyboard sticker sheets in various colors for $2 plus S/H. How soon would they get to South Africa? If you can get the stickers I would do this:
1. Remove existing ink (maybe with acetone or other solvent)
2. Clean, dry, and apply keytop sticker.
3. Apply varnish or clear "liquid plastic" over the keytop sticker. The varnish or clear liquid plastic will prevent the sticker from wearing off and also from peeling off, like an overlay. The varnish or clear liquid plastic needs to be tested to see how it works, but the test would be quick. Clear tape over the sticker also has a protective effect. My experience with the language keytop stickers is that they wear out much more quickly than they peel off. Usually peeling off happens when they overlap the flat surface due to sloppy application.

To me, you can't ever match the look of a cheap replacement keyboard with stickers, but you can get to maybe 70% and if you have the stickers on hand you can do it in less than a day.