You need to make sure you meet the pre-requirements (if any) for an application you intend on installing. Some applications take advantage of the .net framework so make you get that if its not installed.
I'm assuming blizzard is the company of this game. If they are unable to help you address the problem, you should:
a) Research your paticular problem
b) Completely uninstall and re-install the product
c) Return the product if it was purchased recently
Are blizzard telling you that the software is not Vista compatible ?
I run Redshift 5 on Vista, despite the company telling me it wouldn't work, and that they couldn't help me because it doesn't say "runs on Vista" anywhere on the box.
I found that XP compatibility mode didn't help (though that's the first thing you should try), but that "run as administrator" fixed the problem.
If neither of those helps, and the software doesn't say it runs on Vista, then there's not a lot you can do, other than what a lot of us did, and why we're here today, Set up an XP dual-boot on your PC and run your old non-Vista programs from there.
Read the sticky thread before you start and you'll find a whole load of links that'll guide you if you decide to join us.
Try disabling UAC and see if that fixes it. A lot of software that wasnt written for Vista well start working with it disabled. Otherwise, dual-boot as Terry suggests or run a VM of XP (not sure how well it would work under that though).