The problem is with the space in the Program Files name. The XP shell is thinking that the Files portion is an option due to the space. Any file name or directory name that you use that has a space in it must be enclosed in quotes when operating on it at the shell prompt. So, to change to the Program Files directory you would type:
cd c:\"Program Files".
You could also use the old 8 character carry-over and type:
cd c:\progra~1
which is what a true dos prompt requires (take the 1st 6 characters, truncate the rest and add a ~1, ~2, ~3 etc). The problem here is that if you have more than 1 file or directory that begin with the same 6 characters you need to know which numeral follows the ~. Anyway, w2k/xp allow you to use names greater than 8 chcaracters when at the shell prompt so why not. The only thing different is if a name has spaces in it as shownn above.
Here is a link with more information:
http://www.computerhope.com/issues/ch000209.htm
Cheers,
RW