Wow, where to start. I have built or have had built my last few computers from the same place over the last 8 years. What I have found out is that while on the outside you can see all these nice specs of Ram, Processor speed, Video card speed/ram/type of slot, AGP vs PCI..blah..blah...blah...they all go about it in different ways.
Some Mother Boards have a lot of that stuff built in, others add all the options separately. Sound Cards and Video Cards being the two this usually happens with.
Some Motherboards say you can disable their video card, and add your own, great???? But the manufacturer told me once, that if you plan on putting your own video card in, get a different M/B, because even though it says you can disable the onboard video, they still have compatibility problems.
Lots of Ram is a good thing, but now you have to look at the Front Side Bus speed the ram traverses. Not only that, if the M/B has dual channel it's supposed to be faster to break a Gig of ram into two 512 MB ram sticks and run one on each channel, which is supposed to basiclly double your ram speed.
SLI for video cards. Same sort of thing, run two slightly slower video cards together is supposed to blow away a faster single card. They both take 1/2 the load instead of being pushed to the limits I guess.
Hard drives, which one and which standard to use, IDE, or one of the others, One drive or a raid set up with multiple drives.
You may find a Computer with a really fast Processor, but it's Front Side Bus for the Ram is only 1/2 the speed as another PC with a slighty slower PC. Which one really runs faster????
A PC is like plumbing in a way, you can have all the huge pipes you want, to push huge amounts of water along, but if just ONE section is just 1/2 the diameter of the rest, then you have a bottle neck and you limit the water flow with just ONE piece of pipe.
Same thing with PC's, all those components have to work in harmony or in sync with each other, or that Mega fast Processor speed is of no importance. If you limit the Ram to only 16 MB's, that super fast computer is a slug, if it's all Mega fast and you choose an old video card with less ram, some of the newer games will just overwhelm that card and your mega fast Processor PC is still junk. Video cards have their own processors and ram on them to take the load off of the system's Processor, to free it up to do other tasks.
You all make good points, and have different experiences. And all this info will help guide me to a perfect choice I hope...
Debi used to have an HP, and she had good luck with them.
I hear good things about Dell, but then I hear reliability is an issue from some.
Gateway had a nice sounding PC, ran 2nd in the speed testing, but they rated it low for terrible customer service.
Customer service is a big deal, as some have implied. If you've ever worked with one of the customer service people you know what I mean, sometimes they are just stupid, they read a script and go down a list of things to try, not because they know what they are doing, but because it's a procedure they follow. You tell them you have a video card problem, and they end up telling you to change the Oil in your Vulcan...WHAT in the hell does my bike have to do with my video card????

Ok a bit of a stretch, but I'm not far off.
A lot of nice features/specs sound GREAT on paper but some don't really deliver in the real world every day use.
So again, I am listening to all comments and learning from your experiences to help me decide on what to build.
The one thing that really has me confused or is where I have minimal knowledge on, is the hard drive setups.
Does anyone really understand the whole drive concept?
IDE vs ATA vs SATA, vs Raid and Striping? Having two or three drives running at once. I assume it's kinda like having dual channels for the DDR Ram on the M/B??
In reality, I believe the Hard Drives are your SLOWEST point on a PC. They are getting faster, but they can NOT run near the speed of the Ram or Processor, so usually Data transfers from a drive are your slowest point or bottle neck.