Hi,
Running Windows on an Intel Mac is completely viable. If you won't want to be booting backwards and forwards you can use a virtualisation app like Parallels or various VMWare products. I'm not sure how well TG2 would run under those, but if there just a few Windows apps you can't be without then it could be a good way to do it.
Alternatively you can install and boot into Windows using Apple's Bootcamp, a utility which comes with the OS. I've been using both Vista 32 and 64 on different machines using Bootcamp and it's working really well. Installing Vista 64 wasn't so easy, but I managed it in the end with patience :-).
What Oshyan says about TG2 Mac being slower than TG2 Windows is true, but only once you get past 2 - 4 cores, depending on the scene. That's not really an issue unless you're buying a Mac Pro as I don't think Apple sells any quad core machines aside from Mac Pros. In any case it should be possible to bring it into performance parity by the end of the year.
Regards,
Jo