Opinions on custom system build

*takes deep breath*

I've decided to build myself a second system. My current system (AMD Athlon XP 2200+) bogs down pretty bad with all the multitasking I do. Especially since my switch to dual monitors I've realised that I'm gonna need dual processors to keep up. So I'll be retiring my current system to endless number crunching apps I run in the background and build a new system with an AMD Athlon 64 3800+ dual core processor. I'm pretty set on this little baby as its a steal for the price and appears it can be easily OCed to 2.4 Ghz.

Some of the other components I'm less sure about. This is my first custom build so I'm hoping to take advantage of others experience. I've narrowed my search to what I believe will suit me best, but I'm very open to opinions on how these components may interact and other options available.

My choices of mobo seems to be ABIT KN8 nForce4 as it supports my processor, is cheap and appears to be reliable. I'm unsure of the difference between that and the Ultra of the same series. Whats the difference? I was also looking at one with SLI capabilities but since I don't game, or run even a single high end GPU, I dont see the point in paying for that feature.

As far as RAM goes I want 2 GB. The gigaram fits the mobo properly and seems reliable. So does OCZ. Any preferences? Others to recommend? Anything to avoid?

My main concern comes from the PSU. My first inclination was to go for one of the nice n' cheap case/PSU combos available such as this. 480W PSU would likely meet the requirements (1 7200RPM 160GB HD, X2 processor is nice on power, 1 LightScribe DVD burner, possible a generic 52X CD Burner, a mid-range GFX card, 3-4 fans). But it appears that cheap PSUs have a tendancy to explode. I'd hate for that to happen (duh). SO maybe I should go for a nice cheap case, and buy a good solid PSU. I have no idea where to start with that. Theres so little to compare stat-wise. So, what do you all think?

and.... exhale....

/*edit*/

And I'd love to save some money as this is starting to exceed my unofficial budget, so if you know of anywhere I could save some cash and still build a stable system, I'd appreciate knowing! I started out merely intending to upgrade my CPU (and hence mobo) and this has grown a little out of control. :)

Ok... a few things:

1) If you're not a gamer, don't worry about a high-end mobo. The ABIT you mention should do fine and I like the fact that it's PCIX (greater ability to upgrade and PCIX video cards are cheaper than their AGP counterparts on the whole.

2) I've never heard of gigaram, but that's completely up to you. I stick with Kingston, Samsung, OCZ, and Micron. Short of those, I don't have much good for other memory manufacturers.

3) PSU is nothing to go cheap on: www.pcpowerandcooling.com They build the best and you can't beat them for reliability. Those guys know their stuff. The case/PSU combo you posted doesn't list the maker of the PSU and that makes me scared. Don't go cheap if you want your components to last for a long time.

4) As far as a case, I tend not to go cheap there as well. A good case will cool better and be better insulated. Antec is my number one choice in that department.

I know you want to save, but cutting corners leads to parts that go *poof* far too soon. Trust me. I've been through it twice in the past year with power supplies of my own.

going 64 bit with windows might not be a good step right now.
most 64 bit versions have a serious lack in device support.
most software won't make use of 64 bit functionality until windows vista is released next year.
the xp 64 bit / media center 64 bit versions don't support the hardware well enough to bother building the apps for 64 bit.

other than that one issue, ober is right.
save where you can ( less ram, slower cpu ) but not where it is critical to base operation, like power supply and cooling.
it's easier to upgrade ram and cpu than to replace most of the system because of cooling failure or power supply problems.