This may not be typical, but I had some problems installing the OS on my system. I had a 32-bit copy of XP (full edition) and the Vista Ultimate upgrade. Because Vista was an upgrade, I had to install XP first and then, once XP was running, install Vista from there. Because my system had 8 GB of RAM installed, XP simply would not install. It would get to a certain point and fail. I spent over a day trying to figure out what happened. I finally had to take out some memory until I had 2 GB (I had four 2GB dims) and then XP would install. So you may want to leave out some of your memory (if you get more than 3 GB) while initially installing XP.

Nope, it will still matter if you're multitasking. The assumption that you also need more memory to use a 64 bit OS is untrue. Programs demand memory, 64-bit handles it differently, but it won't need for example twice the amount of memory (addressing).

Also, note that not every 64bit edition of Vista actually really supports more than 4Gb.



With 64-bit gaming, depending on the efforts of the developer, it will often improve the overall visual quality because of the higher detail, but naturally at a loss of performance. It'll obviously ask a bit more of your processors, but it's not a world a difference.

It's like running a game at insanely high settings with a top of the line graphics card, it might run 40fps... bút look superb. Same game, lower graphics settings with a budget 3D card might run at over 60fps, but look horrible.

Cheers

Frank I dont know how much of a hurry your in but if I was you I would get the system you want then install xp, (provided you have a legal copy and not an oem.)

Then I would wait untill windows 7 comes out late 2009, 2010 and install that OS at that time.

The main reason is you will eventually want to upgrade to win 7 anyway, as it will be much better than vista, and you will be kicking yourself if you pay good money for vista when win 7 becomes available.

As far as your hardware goes, I would personally go with some NVIDIA SLI technology. Right now they have 3 core, even quad core video.

Here is the stuff you need to be SLI ready:

http://www.slizone.com/object/slizone_ecosystem.html

I would go with (it is dual gpu)NVIDIA Geforce 9800 gx2
http://www.nvidia.com/object/geforce_9800gx2.html


but there are a lot of options out there; take your time and dont buy on impulse.

Id also go with a RAID

Thanks for the comments. Waiting for Win7 is a good idea. But I heard it will take about a year from now.

Regarding SLI: I am afraid of it. Many game magazine reviews showed that it works only with special software. In most cases games use only one kernel of the card and so you get not advantage over a non-SLI single gpu solution. But it drains more power.
And if your game supports SLI then you get some micro-delays during rendering because of the synchronization of both cards.

Right... but those are the same magazines that even to this day are incredibly pessimistic about the Dual Core and Quad Core performance increase of the latest processors...

I really wouldn't put too much faith in what those magazines. There are practically always performance boosts... whether it's worth the money or not depends a lot on your budget also.

Just look at the PS3, the Xbox360 .. both already have multi-core processors in them for a good reason. All the multi-platform games will take advantage of multi-core PCs because they are designed around multi-core systems.

I'm thinking the next generation of consoles will also have dual or multi-core graphics cards.




Don't worry about that. You really won't notice this... it's a lot less than a split of a millisecond and it won't ruin the performance increase at all. The relevance of these delays is really near zero when it comes to the performance in practice.

You won't get twice the performance with two 3D cards in SLi, but you will get a considerable boost. Some think it's worth it, some think it's expensive,

Cheers

Yes, it is expensive, but this is not my biggest concern. It will also consume much power and electricity became more expensive lately in this country.
Another problem is heating. I would like to have a quiet system. So I probably need some special cooling devices. But an expensive SLI card probably will not help in this matter.

@Frank:
What are you're concerns about Windows XP Pro 64-bit?
Its an 64-bit operating system and thus can adress more than 3 GB Ram.

Xarthor: How are the 64-bit drivers for XP Pro 64?

Frank: I am running an SLI card and I have had no compatibility issues with it whatsoever. I am running a variety of 3D applications (modo, MAX, Silo), running games from the original Half-Life to UT3, running basic office applications like Word and Outlook, running GameStudio, browsers ... and nothing has so much as given me a hick-up.

Thanks Dan: How about OpenGL? Many 3d applications are based on OpenGL. Does it run faster on SLI or just the same like a one-board graphic card of the same type?
I often read that software needs special optimization to use SLI efficiently.
And how about multi-monitor support? Actually I can imagine that multi-monitor and SLI should be a perfect symbiosis.