In terms of memory, yes, Vista x64 will be the best choice. Eventually we'll hit games that require more than 2 GB of RAM, and then more than even the 3 GB you can allow with a switch to a program in XP, so long-term, 64-bit is the way to go. Who knows, maybe Civ5 will be the program that busts down the memory gates? Civ4 indicates that may well be the case, but then again, considering that Civ3 didn't indicate that at all (rather processing power), Civ5 may or may not demand gigabytes of memory.
For graphics interface, you're pretty much stuck with PCI-Express right now. And I don't think it's going to disappear especially quickly. ATI still releases cards with AGP interface and even PCI. So I wouldn't hesitate to go with PCI. You'll be waiting quite awhile otherwise, unless I've somehow missed some major news.
As to CPU sockets - those seem to be pretty steady on the desktop side. But note that having a fast Front Side Bus is very helpful for upgrading. If your motherboard only supports a 800 MHz FSB and you put a 1600 MHz FSB CPU in it, it will run (provided it is socket-compatible), but only at half its stated speed. Which could end up it it actually being a downgrade. You'll probably want one of the 1333 MHz FSB Core 2 Quads if you're concerned about upgradability. See
http://en.wikipedia.org/wiki/List_of_Intel_Core_2_microprocessors for an overview of all the processors Intel offers in the Core 2 lineup. Or
http://en.wikipedia.org/wiki/List_of_AMD_Phenom_microprocessors for AMD. I would assume the same principle applies to HyperTransport, thus making the faster HyperTransports better for upgradability, but I don't know that much about AMD processors so I'm not sure.
I think the real reason to go with Vista is that it is faster when using high performance parts. No amount of tweaking or third party programs will change the underlying architecture of XP.
Vista faster than XP? I'd like to see the tests that show that. So far the only thing I've seen show Vista as faster is wPrime, a CPU-test. I'm not saying it's impossible, just that most tests show XP as being faster.
Zelig said:
Honestly, crashes are mostly based in user error (including poor choices of software), or hardware problems.
This could be interpreted as Civ3 being a poor choice of software...which would be blasphemy.
I wonder if next gen devices will come with XP drivers as well?
Well, there's no guarantee, of course. But I think most will, at least in the hardware realm, for at least another three years. nVIDIA supports Windows 2000 through the GeForce 7 series, for example, and thus 2006 is the first year they released a mainstream product that does not support Windows 2000 (GeForce 8 series), five years after the successor to an OS that had a much smaller market share when succeeded than XP did. And the GeForce 6 series still supports Windows 95, making it supported for seven years after its successor was released.
Peripherals might start phasing out XP a bit sooner than that, but even then I doubt it will be too soon - drop XP support too soon and they'll lose a significant number of potential buyers. Just because you're buying a new printer or digital camera doesn't mean you've got the newest operating system - it could well mean that your old one is broken.
It is true that paying for both XP and Vista is no fun, though. Perhaps you'd be best off getting Vista Business. That way you'll be able to downgrade to XP Pro if you do encounter Vista problems, but if not, you'll be able to use Vista. And if you do downgrade to XP Pro and later find you need Vista for something, you can undo the downgrade and go back to Vista. It's not quite as good as having both, and would require you to find an XP Pro disc if you decide to downgrade (but it can be any XP Pro disc - even one someone else has already used - just activate by phone), but it's the next-best thing for no increased cost. About the only thing you lose out on is Media Center.