Don't worry - I'm not going to inflict a blow-by-blow technical details post on you. This is more to point out that the Release Candidate 1 for Microsoft's next operating system is now free to all comers, and to address the question of whether we gamers should care about it a lot, a little, or not even slightly.
Personally, I'm going full-pelt for a yes, whether you're running Vista or good ol'XP. It's free from a lot of the bloat and associated chugginess of the former, but adds in a spot of whizzbang and the DirectX 10 support (and 11 too, in theory) that that the latter lacks. Best of all, RC1 will continue to run until July 2010. So if you haven't yet moved from XP to Vista and have a DX10 card, you now get to try it (and DX10's) best bits without spending a penny or breaking any laws. I've been running an earlier version 7 as my main OS for a while now, and I can honestly say I've been a lot happier with it than I ever was with XP or Vista. It's definitely a better option for a laptop or other lower-spec system than any version of Vista, as it's far less memory hungry.
A Release Candidate, incidentally, is just that - a fundamentally finished version that Microsoft hopes is fit for release. The major wrinkle with it is that you'll not be able to simply upgrade to the final, final version come July 2010 (or whenever you end up buying Win 7, which is due for release later this year), but rather will have to do a whole new install. So this is probably a second-hard-drive job, unless you subscribe to the philosophy that giving your Windows a thorough clean every now and again keeps performance tip-top.
For all Microsoft's bally-hoo, there aren't really any gaming-specific features worth trumpeting in either Vista or Win 7 (bar the fact that a 3D card driver crash doesn't usually require a system restart, but can instead recover itself), but it's definitely a nicer desktop environment than, arguably, any other Windows to date. If I get the chance, I'll run some comparative benchmarks to see gaming performance stacks against XP and VIsta in hard numbers. Grab RC1 (in either 32 or 64 bit flavours) from here - it's only 2.5Gb, surprisingly.