Exchange 2010 uses RPC Client Access Service and this is only supported in Outlook 2003 and upwards.
So there has been little "official" testing of anything older.

That's not to say it won't work it's just to say it's not supported.

You will also loose out on a lot of new features.  Outlook 2010 is in beta at the moment and is the only client that supports the online archive function of Exchange 2010.

Supporting ref:

"From a supportability standpoint this is correct. Outlook 2000 and XP may work, but they are not officially supported nor tested."
http://social.technet.microsoft.com/Forums/en/exchange2010/thread/637ef274-2c0b-44cd-af81-1ed9b0c06084

"Microsoft does not officially support Outlook prior to 2003 against Exchange 2010, so Outlook XP, Outlook 2000, etc are not supported."
http://www.pcworld.com/businesscenter/article/183045/outlook_2010_sneak_preview.html

ok, so it is a dumb idea but it definately won't work?  Why does Microsoft only say something like "not all features are supported"  I don't care about new features right now, I just want to get Exchange 2010 running without having to wait for Office 2010 to come out.

It's not supported doesn't mean it won't work!
It just means it's unsupported!

It may well work there just hasn't been any "official" testing on it.

Hi,
As Glen said it has not been tested. See one reason given by MS was that there no time to test Outlook 2000 with Exchange 2010, as it has been out of support for already. Why would you want to upgrade to 2010 in such a case?
Yes it would work, but no one from MS will help you if you get stuck since it is not supported

gupnit, when you say "Yes it would work" is this from experience or just a guess?  No disrespect meant. I am not worried about getting support from Microsoft.  I plan on upgrading to office 2010 when it is released but I would like to work on the Exchange 2010 upgrade now.  There are many benefits to upgrading but my main reason for wanting to do it now rather than later is that there is nothing else to do in here in winter and funding for the server is approved. I hope to then do the office 2010 upgrade in the fall and get the full benefit of the new server then.

I think it's an educated guess from both of us that it is more likely to work than not.
If I had a copy of Office 2000 I would try it for you.  Let me see if I can dig one out.

Hi,
I will have to dig in to my notes, during a discussion within Microsoft guys and MVPs, there was this question and it seems one of the MVP tested it. I have not tested, as none of the environments I manage have Outlook 2000 anymore. So, as a honest answer, this response is from an experienced guess.
My strategy would be - Setup Exchange 2010 on one server in Lab, install Outlook 2000 in the environment and test. But let me warn you there can be issues that might not crop up during testing but would once you go live. I would say a good idea would be to wait some more time for Outlook 2010 RTM and then go for Exchange 2010 depoyment. Infact you can go with Outlook 2010 even irght now, and by the time you would be installing Exchange 2010 (i mean there would be lot of planning that would be required - read one of my artcile - http://www.nitingupta.in/blogs/index.php/2009/12/13/capacity-planning-tools/ for what I mean.)
Let me know
Thanks
Nitin

I will test it today in a live environment :-)

OK, I havea copy of Outlook 2000 and 97 and am in the process of installing a Windows XP VM to test on,.........I will report back!

Cheers.....and my $.00000002 it will work :) 100%  !!

me too!

thanks guys

good enough for me, I think I will go ahead with the Exchange 2010 upgrade, update some of my older Pc's to Office 2007 and let the others use outlook web until office 2010 comes out.

Great.....!!

I can get Outlook 2002 to work with Exchange 2010 but not Outlook 2000.  Microsoft needs to understand that some of us need this for testing purporses, not for "real work" purposes.

FYI I'm observing the same behavior with one of my customers; Outlook 2002 does connect up but 2000 does not.