Eh... I can't be tossed to re-read the whole thread. Aside from what's already been suggested, I kinda lightly skimmed some of the other stuff... but, if you're having trouble getting your ram recognized, I would make sure you checked the mobo specs.
The obvious things are:
Make sure you are using the proper RAM (DDR vs. DDR2, the correct frequency/Mhz, etc.). You can't really mix and match between certain types i.e. I'm pretty sure you cant use DDR and DDR2 RAM together. Your mobo probably has a maximum Mhz that it can use. Also, ideally, you
shouldn't mix RAM with different Mhz, although it should still work, the "speed" of the RAM will drop to the whichever has the lowest. Finally, much older mobos and apparently the more recent mobos require RAM to be paired. I'm pretty sure older ones definitely required paired RAM. There was a time where you could have non-paired RAM (my sister's machine actually only has 3 RAM slots). But I think nowadays, newer mobos recommend having paired, dual channel RAM.
As for the PSU and what not... I dunno how old your case is... but I've been told you shouldn't get any weird shaped cases. I'm assuming that you're also upgrading your own machine (I'm obviously not an expert myself), but I've found that ATX compatible cases seem to be the best kind, or the most popular at least. Seems to be a standard form factor, and most parts seem to be designed to fit into them, so I'd say you're less likely to run into troubles involving wedging things in to make em fit.
Incidentally, I managed to build my machine this weekend. Well... actually, I had the hubby do the majority of the work. Heheh. I kinda futz around with it for awhiles, before gettin frustrated with things and ultimately makin him do it. He was originally supervising, but then I got fed up listenin to his advice and wanting to do it my own way. And he got fed up with me bitching and ignoring him and he ended up wanting to just do it himself so I would stop complaining about it. I struggled a bit, but I managed to follow along and I think I can handle putting my next machine together. I did manage to install the CPU and CPU fan. Lol. I started to put the mobo in, but then he ended up "correcting" me. And then he plugged in all the rest of the wires.
It probably would have went faster and smoother that way if he did it all himself from the get go. Lol. In the end, it wasn't so bad.
Anyhew, one piece of advice I didn't stick to, is that you really should check the specs of your parts and make sure everything is compatible and what not. Not that I had any serious issues... but one thing is, my case has a built-in firewire port, but I stupidly chose a mobo that does not support firewire.
I didn't know better, because I didn't know what IEEE-1394 meant, and I didn't think it was all that important. If I really needed a firewire port, I suppose I could install a PCI card Or just use a firewire to USB converter or what not... but still, it would've been nice to be able to have that built-in port working. It seems like such a waste.
Anyhew, I'm hoping to have my new machine up and running by tonight. I'm split between finishing updating some of my other hacks... or finishing installing all of my software onto my new computer.
Ste