Hello Jamemoff, if anyone is building a new system and also needs a Operating System, then their is no reason not to go with Microsoft Windows Vista at this point in time.
When Windows Vista was first released sure their were a few problems with compatibility, however, this has now changed and the support for Windows Vista is now excellent. The majority of the manufacturers out their have now released 64-bit drivers for their hardware and as regards to software, once again, the majority of software now work perfectly fine under Windows Vista. Their have also been a few problems within Windows Vista but the majority of these are now fixed thanks to the Performance and Reliability packs that Microsoft have been releasing along with other updates. Now their are still a few problems around for example, slow transfer rates across networks, from one folder to another but this seems to be only affecting a few people and not the whole user base that is using Windows Vista. Though I believe this is set to be fully fixed in Service Pack 1 (Fiji) which is due out in the first quarter of next year. This certainly isn't affecting me and I think the same goes for a lot of people as well.
Now as far as game performance goes, in my opinion, it is now exactly the same as Windows XP, I notice no slowdowns what so ever. Now I understand that some people are still having a few problems but I believe these are very far and few between these days and I feel that some people tend to over exaggerate things a tad.
Since there are a number of different versions of Windows Vista, you may not be completely sure on which one to purchase if you are looking to by Vista.
Here is a great graph that compares all of the editions of Windows Vista with one another. The two you are most likely looking at are Windows Vista Home Premium and Ultimate. I have used both Windows Vista Home Premium and Ultimate and in my opinion, Ultimate is not worth the extra £50 over Home Premium.
Now you may also be debating over either purchasing the 32-bit or the 64-bit edition of Windows Vista. If you have a processor that is capable of handling 64-bit instructions then their is no reason to go for the 32-bit edition. You won't see a massive performance increase going from a 32-bit to a 64-bit operating system as of yet since many programs have been written for 32-bit architectures. However this will be changing in the future because with 64bit being more recognized, more and more programs will be written under 64-bit architectures. When programs are released that are written specifically for 64-bit, you will then start to see a performance increase from 32-bit programs.
Many people think that the only advantage to a 64-bit Operating System at the moment is so that you can access more than 4GB of memory, this isn't entirely true and if you want to know more about this, then
this article is fantastic and well worth reading.