Talking about XP Software Compatibility in Vista
During our testing, one of the most interesting areas of Vista was if our Windows XP compatible games and applications would just work in the new OS, without having to go to great efforts to get them working.
We are happy to report that most XP based applications and games we threw at Vista worked with very little to zero problems. We tried a short list of about 20 XP based software (Firefox 1.5 and Firefox 2 PR, 3DMark05 and 3DMark06, Winrar, utorrent, Spybot Search and Destroy, Cinebench 9.5 and CPU-Z) and game titles (such as Doom 3, Quake 4, PREY and Half Life 2) that we most commonly use and out of those 20, only 3 didn't work - out of those three, two installed without a problem but wouldn't execute. One which wouldn't execute was HDTach (a HDD benchmark program) - when trying to execute, we got a dialog box saying that either Windows 2000 or XP was required and we had no way in. This should be a pretty easy fix as it seems like most XP software will be able to work in Vista but I'm not a software developer, so I can't say for sure.
Another was AVG Free anti-virus which installed without a problem but wouldn't execute as Vista believed its driver was not fully compatible with Vista. It might be a simple case that AVG is not certified to work with Vista yet or the program doesn't work in Vista yet or maybe we just did something wrong.
We believe most companies have been working on Vista support for many months now for their software and come the release of the OS by Microsoft, you will see a multitude of software companies release updated versions with Vista support or special versions just for Vista - just for example, companies such as ATI and nVidia have now long had Vista graphics card drivers on their website, so don't think companies are sitting idle, they are working hard on making everything work well in Vista.