Thank you, Sylvanas.
The rig will be a general-purpose box, used for home office stuff, web and email, photo editing, watching DVDs and streaming media. No video encoding at this point. Gaming is light: I like flight sims, but can't do FPS games without becoming ill. It's on 24/7, doing Folding @Home when not otherwise occupied. It replaces my Athlon 64 3000 that died late last year, after 6 years of use, when the PSU died and took the mobo with it. I'm making do right now with a Celeron D/onboard graphics box that a friend gave me. Even with 2GB of RAM from my old rig, it struggles with almost everything now.
The Newegg Biostar/720 combo is a killer deal right now but, since I don't do a new build every couple of years, I'm willing to stretch a bit for the long haul.
I may overclock a bit. I bought a Noctua cooler just in case, plus I like quiet, I'm Folding 24/7, and it get's bloody hot in my place in the summer if the air conditioner isn't on. Rock-solid reliability is my prime criterion.
I probably will run with onboard video initially and add a discrete graphics card later, after I've put new tires on the family van. Something on the order of a 4830/4850 or GTS 250 should do fine for me. Somewhere down the road I"ll pick up a bigger and better (non-TN) monitor as well.
4GB of DDR-3 seems to go for about $5 ($60 vs. $55) more than 4 GB of DDR-2. The real price delta here is from Newegg's $40 combo discount + $10 rebate on the Biostar/720 combo.
Here's what I already have:
Corsair TX650W PSU (purchased from Newegg 2 weeks ago)
Samsung SATA DVD burner (on special yesterday at Micro Center, too cheap to resist)
Noctua NH-C12P cooler (enroute from Heatsink Factory)
Antec Sonata case (original version, from my old rig) - I may replace this
M-Audio Revolution sound card (from old rig)
Monitor, mouse, keyboard