SOS - Building Computer - Kinda Rusty On New Hardware

Just to bring you guys up to speed on my situation - The last computer i built had an ASUS A7n8x-x Nvidia 2, 9700 Radeon, Corsair XMS Memory. All the computers i've built have followed the ASUS mobo formula and ATI cards, but my little bro is helping me with a new computer- being at 15 - he figures his word is gold and im rusty with all the new hardware coming up.
I've slimmed my questions down to get specific answers, real word experience would be extremely appreciated as i've been out of the loop for a while.

ATI motherboard chipset (Express 200) Vs. Nvidia motherboard Chipsets. (Nforce4)

AMD procs are sticking, never built anything else and never had problems.

RAM - I've always gone with the caviar of ram -Corsair XMS- but is there any real world power gains vs. more economic brands?

Harddrives - Seagate sounds good to me.

The card manufacturers, are there any general companies i need to stay away from ? Sapphire ? MSI ? ASUS (never had problems with them) ?

I'm looking for a powerful and above all -RELIABLE- gaming machine. This will be the xmas present for my little brother, helping him build his own gaming rig, and it would suck to the utmost degree if it broke within 6months.

I've already have an idea of what im going to use, but not quite sure if there would be any major issues with it yet.

*Motherboard
ASUS A8N5X Socket 939 NVIDIA nForce4 ATX AMD Motherboard $92

*Processor
AMD Athlon 64 3200+ Venice 1GHz FSB Socket 939 Processor $178

*Video Card
SAPPHIRE 121SR Radeon X700 128MB DDR PCI Express x16 $104

*Memory
CORSAIR ValueSelect 2GB (2 x 1GB) 184-Pin DDR SDRAM Unbuffered DDR 400
$183

*Harddrive
Seagate 8x 120Gb - Have it

*Cd Drive some bestbuy $20 special.

*power supply
Thermaltake TR2 W0070 ATX 430W Power Supply $40.00

Havent decided on the case, probably a cheapy $20 case that ill add some fans on.

-------------------------------------------------------------
Total : $596.99 including shipping (1-5business days)

Maybe too much memory for a computer like this ? Trying to keep it under $600. Thoughts and opinions appreciated.

The amount of RAM is fine. Will your bro OC?

overclocking isnt a concern. i just want to make sure that this computer will still be running reliably for years to come. Just making sure that the silicone on parts wasnt replaced with cost saving peanut butter or some other possible catastrophe, i heard something about some recent ASUS motherboards having their heat sinks fail, so i was a little concerned.

Think all the parts are equally balanced?

ASUS mobos do tend to have some faulty caps every once in a while. In any case, if you don't need OC'ing, then the Chaintech VNF4 Ultra would be a better (cheaper) choice.

I'd also get an nVidia vid card, but that's just my opinion, there's no real technical evidence that one's better than the other.

The rest looks fine, but it's a shame to see a 3200+ Venice not getting the max out of it. ;)

i would go for ocz 2 gig, an msi board or BFG RNF4U nForce4 Ultra (Socket 939) PCI-Express Motherboard(lifetime warranty on their stuff ), go for a xfx card they are gforce range or bfg for the lifetime warranty. maxtor sata or Western Digital . with the chip either go for the 3000 or 3500 64bit i dont see any point buying a 3200 over a 3000.
My card and memory cost as much as your whole pc if not more.

I've just gone over a few review sites and saw Express 200 lacking behind the GeForce 6100/6150 boards. I checked a few places and they all pretty much had the same results. The difference was minute, but why settle for less, you know?

STABILITY|PERFORMANCE

AMD OPTERON 146 2.0GHz 1Mb $165.00 (http://www.tankguys.biz/opteron-cache-socket-p-1420.html?osCsid=fb6da369 0ca574fb309c8ca24400897a)
BIOSTAR TFORCE6100-939 $75.00 (http://www.newegg.com/Product/Product.asp?Item=N82E1681 3138264)
OCZ PC3200 OCZ4001024V25DC-K 1Gb DDR400 CL2.5-4-4-8 $71.77 (http://www.newegg.com/Product/Product.asp?Item=N82E1682 0227039)
NEC ND-3550A DVD BURNER BLACK $39.75 (http://www.newegg.com/Product/Product.asp?Item=N82E1682 7152058)
NEC FLOPPY DRIVE BLACK $7.99 (http://www.newegg.com/Product/Product.asp?Item=N82E1682 1152005)
FORTRON SOURCE AX400-PN ATX12V 400W $39.99 (http://www.newegg.com/Product/Product.asp?Item=N82E1681 7104953)

OPTIONAL
XFX PV-T42G-UAD7 6800GS EXTREME XXX 256Mb [485MHz|1100MHz] [12PP 5VP] PCIe $205.00 (http://www.newegg.com/Product/Product.asp?Item=N82E1681 4150118)
G.SKILL F1-3200DSU2-1GBFX 1Gb TCCD DDR400 CL2-2-2-5 $151.82 (http://www.newegg.com/Product/Product.asp?Item=N82E1682 0231035)