Can Windows 7 Home Premium be upgraded to 7 Professional if I Have the Professional DVD and Product key

You can't upgrade from Home to Professional. You will need to do a clean install.

I was wrong, according to this you can use Anytime Upgrade from Windows 7 Home Premium to Windows 7 Professional.

That is incorrect.  See this Microsoft Technet page:

http://technet.microsoft.com/en-us/library/dd772579(WS.10).aspx
Windows 7 Upgrade Paths

BTW, although I hate to contradict Rick or anyone for that matter, I have done three upgrades from Home Premium to Professional for exactly the same reason as you are doing it for - to get on a domain.  All went flawlessly and all were on HP notebooks.  All were done using Anytime Upgrade. The key is getting the right lic key.

Sorry to Rick though.

Phew, someone else has agreed with me - I don't feel so bad now!!

Since you have a DVD - I assume this is a corporate key, in which case it should be fine.

Of course you can. You need to use the Windows 7 "Anytime" upgrade: http://www.microsoftstore.com/store/msstore/en_US/buy/pageType.product/externalRefID.C562285E

Basically, if you already have license key... just enter it. This is assuming that the license key that you have is for a Toshiba also (OEM) since your Toshiba comes with the OEM license for Windows 7 Home.

Follow these instructions to do the "Anytime Upgrade":
http://windows.microsoft.com/en-US/windows7/help/videos/upgrade-to-another-edition-of-windows-7-by-using-windows-anytime-upgrade

Bits ...

As long as you have a key and the disk you shouldn't have any problem upgrading it.

Thanks to all.  To rick, no problem, you corrected yourself.

Agreed!  By all means an Anytime Upgrade can be done and it only takes 10 minutes.  It doesn't get any easier than that.  I know you already have the product key - and that is all you need, but Microsoft actually sells the Anytime Upgrade you are looking for, so yes, you can.
http://www.microsoftstore.com/store/msstore/en_US/buy/pageType.product/externalRefID.C562285E

To all,  
 the Anytime upgrade failed and when I tried to upgrade from DVD it told me to use Anytime upgrade

OK, if you have a valid license, which you are telling us you have, then if you can scout around for a another machine that has Pro on it (Toshiba OEM), then perform update using its key, then maybe change product key afterwards.  I have performed side-by-side upgrades, but have never bothered to change product key, cos I'm lazy!!
If you have trouble getting a Tosh key, let me know.

I'll try that now.  Mine has a key.

I just checked two 7 computers and their keys format is xxxxx-xxx-xxxxxxx-xxxxx.  The key I have and the Anytime upgrade want xxxxx-xxxxx-xxxxx-xxxxx-xxxxx.  Any suggestions?

I'll need to PM you as the info is sensitive, how can you be contacted?

I'll bet it actually reads:
xxxxx-OEM-xxxxxxx-xxxxx

Right?  This is not your product key ... only a generated representation, indicating it is an OEM (Toshiba, Dell, HP, etc.) key.

You need something like Magic Jelly Bean to retrieve the actual product key used to activate it.  HOWEVER ... If this was installed from the factory, there is a very good chance the key that will be retrieved will NOT match what is on your computer, as OEM's usually use a generic, self/auto-activating key.

@ComputerAidnz
jsitman@spcala.com

My computer at home was installed by me.  I'll look up MJB

MJB gave me the same key as what was displayed in "change product key"

Actually, looking at the website for Magic Jelly Bean, only their paid version will work on Windows 7, so you'd have to find a different utility for it to work on Windows 7.  If you are looking for a possible incompatibility with product keys, you can save yourself some time ... all Microsoft Windows product keys are 25-character alpha/numerics.  System properties shows only a generated value to represent the type of key used.

Try Belarc Advisor www.belarc.com. It's free and will give you the serial number plus tons of other information.

Bits ...