The Gaming PC is Back ON!!!!

[Professor S]

Ahhhh, well it looks like I don't need a new car all that soon, so I'm still shopping for that ultimate gaming PC for the best price. I recently visited a reputable internet company that gave me this build:

CASE: CoolerMaster Stacker 830 Mid-Tower Case W/ Side-panel Window

CPU: (939-pin) AMD Athlon™64 FX 60 Dual-Core CPU w/ HyperTransport Technology REG $4999

MOTHERBOARD: (Sckt939)ASUS A8N32-SLI Deluxe nForce4 SLI Chipset SATA RAID Dual PCIE MB w/GbLAN, USB2.0, IEEE-1394, &7.1Audio

MEMORY: 2048 MB (1GBx2) PC3200 400MHz Dual Channel DDR MEMORY (Corsair Value Select)

VIDEO CARD: NEW! Quad NVIDIA® SLI™ Technology Featuring Four GeForce® 7900 GPUs Totaling 2GB Memory Video

LCD Monitor: ViewSonic VA1912WB WideScreen 19" Color TFT Active Matrix SXGA LCD Display Monitor

HARD DRIVE: Gaming Hard Drive (10, 000RPM SATA150) (SATA150 - Western Digital Raptor 150GB 10, 000RPM 16MB Cache WD1500ADFD)
Hard Drive 2: Gaming Hard Drive (10, 000RPM SATA150) (SATA150 - Western Digital Raptor 74GB 10, 000RPM 8MB Cache WD740GD)

Optical Drive: (Special Price) LG GWA-4161 16X DVD±R/±RW + CD-R/RW DRIVE DUAL LAYER (BLACK COLOR)
Optical Drive 2: SONY 16X DVD-ROM (BLACK COLOR)

SOUND: HIGH DEFINITION ON-BOARD 7.1 AUDIO

3 year warrantee

All this for $4,783 with free shipping and AoE 3 included. I think this is an amazing price (correct me if I'm wrong) but I do have a concern. It comes with a liquid cooled heat sink, but it only covers the processor and not those 4 cards. Otherwise it does have two other cooling fans plus the fans on the cards. How much will heat be an issue if the Quad SLI is only air cooled?

Also, I want to upgrade to 4 gigs of RAM, but they don't have that option. Can I upgrade myself?

Also, what about the Physics card? Is it worth it?