Here I go again (spec'ing new system)

I've had a lot of fun building and fiddling with my rig... got a lot of key mistakes out of the way without spending too much money 
But old Bessie has proven herself unworthy to run FS9 to my liking after about 18 months of tweaking and baby-step upgrades...by the time I properly upgrade the key components, i'll be basically building a new system , so...
Love my WD drives (still going strong!) ; probably will move both to the new case, or maybe leave the smaller one behind in what will be a system devoted to utility-type stuff... but everything else will be upgraded. The Lite-on DVD/RW is great, too... I'll most likely get the same or similar, so i have one in each system.
Been window-shopping online; got lots of time as I don't have the loose shekels yet (around $1K is what i'm looking to spend), and I have a few ideas; would love to hear comments, as I'm already experiencing a little overload here.
For starters,I'm not looking to overclock; not very interested in any other games, just want a system that, when optimized conservatively, will reliably deliver 30fps or more in FS9- with no jaggies- no matter what I add or what settings I use.... preferably with no smoke coming out of the case.
Other than FS9, I will probably do a little A/V and photo editing, but nothing fancy.
I like AMD; gonna stick with that. The 64 4000 (Clawhammer) looks good to me, but only if it will really solidly support the gfx card, which I'm thinking will be a 7800GT, most likely eVGA. Absolutely a minimum of 1GB RAM at 3200; anybody know anything about the Gigaram modules? Seems like a pretty good deal at New Egg, but I smell a gimmick ("multilayer" or somesuch). And would 2GB be worth it?
I'd really like to get a module (or modules) with a heat spreader, seems smart to me... unless the gurus out there think it's not worth it (BTW, I'm not looking to water-cool or anything; just gonna get a basic but solid case with a side duct and front and rear fans... and a powerful PSU; probably 450W).
Where I'm sorta lost is on mobos. I want at least a 400FSB, gonna go PCI express, need onboard LAN, and I'm toying with the idea of leaving my (pretty solid) Audigy SB 5.1 card in the old rig and using onboard 6-channel audio. Other than ripping and playback (all stereo right now), I don't do much audio work, but that may change (surround recording, editing, 5.1 speakers)...I could just add a good sound card later, but not if I find a mobo with better-than-average onboard audio that supports what I need for good flight-simming. I was looking at the DFI UTRDX200 "LANparty" board, but...? What do you guys think? My current board is an Epox; clunky but reliable... never heard of DFI. The DFI board claims 800 with hyper-threading support; does this benefit me in any way with the CPU, RAM, and gfx card specified? Overkill?

But old Bessie has proven herself unworthy to run FS9 to my liking after about 18 months of tweaking and baby-step upgrades...by the time I properly upgrade the key components, i'll be basically building a new system , so...
Love my WD drives (still going strong!) ; probably will move both to the new case, or maybe leave the smaller one behind in what will be a system devoted to utility-type stuff... but everything else will be upgraded. The Lite-on DVD/RW is great, too... I'll most likely get the same or similar, so i have one in each system.
Been window-shopping online; got lots of time as I don't have the loose shekels yet (around $1K is what i'm looking to spend), and I have a few ideas; would love to hear comments, as I'm already experiencing a little overload here.
For starters,I'm not looking to overclock; not very interested in any other games, just want a system that, when optimized conservatively, will reliably deliver 30fps or more in FS9- with no jaggies- no matter what I add or what settings I use.... preferably with no smoke coming out of the case.

I like AMD; gonna stick with that. The 64 4000 (Clawhammer) looks good to me, but only if it will really solidly support the gfx card, which I'm thinking will be a 7800GT, most likely eVGA. Absolutely a minimum of 1GB RAM at 3200; anybody know anything about the Gigaram modules? Seems like a pretty good deal at New Egg, but I smell a gimmick ("multilayer" or somesuch). And would 2GB be worth it?
I'd really like to get a module (or modules) with a heat spreader, seems smart to me... unless the gurus out there think it's not worth it (BTW, I'm not looking to water-cool or anything; just gonna get a basic but solid case with a side duct and front and rear fans... and a powerful PSU; probably 450W).
Where I'm sorta lost is on mobos. I want at least a 400FSB, gonna go PCI express, need onboard LAN, and I'm toying with the idea of leaving my (pretty solid) Audigy SB 5.1 card in the old rig and using onboard 6-channel audio. Other than ripping and playback (all stereo right now), I don't do much audio work, but that may change (surround recording, editing, 5.1 speakers)...I could just add a good sound card later, but not if I find a mobo with better-than-average onboard audio that supports what I need for good flight-simming. I was looking at the DFI UTRDX200 "LANparty" board, but...? What do you guys think? My current board is an Epox; clunky but reliable... never heard of DFI. The DFI board claims 800 with hyper-threading support; does this benefit me in any way with the CPU, RAM, and gfx card specified? Overkill?