run win7 with XP on mult PCs on server?

[kitch33]

I have not had very good experiences with our IT guy at work--he has some odd ideas like saying that Mozilla products are for "home users" only and insisting we can't use Firefox. I went ahead and purchased a new Dell Studio desktop with Win 7 for my office (without his advice, which annoyed him) and he is now insisting that I can't run Win 7--that all computers on the network must be on the same operating system (most are using XP), and he claims all computers must have same software, and has moved people "back" to Excel 2004, etc, removing newer editions.
I can't find any evidence to support this. He claims that the server won't run properly if we use different operating systems. I think he is misguiding us. Any input?

[EzyStvy]

Someone hired your IT Guy for a reason You might want to speak to the hiring manager.

You didn't mention what your server does/what functions it serves so its impossible for us to guess.