Why not just try the 90-day trial? That should give you plenty of time to evaluate it and see if there are any issues. Or else try one of the Express products. OTOH, if you're not planning to use any of the new stuff and you're not using, e.g., WPF, then there's not much point. Oh, I just spotted that your company already has 2008. In that case just get one or two developers to install it and play with it for a bit - or run it in a virtual machine.
Kevin