Actually, now that I've looked at it again, my PSU is only 300W. That may change things a little. Here is all the spec I could find on my desktop PC(tell me if I should get a PSU first):
Asus Essentio CM5571-BR003 Pentium Dual-Core E5400 2.7 GHz Desktop PC
General Features:
Microsoft Windows 7 Home Premium 64-bit pre-installed w/CoA
Intel Pentium E5400 2.7 GHz dual-core processor
800 MHz FSB speed, 2 MB L2 cache
Intel P43/ICH10 chipset combination
6 GB DDR3 SDRAM
Serial ATA DVD±RW DL drive
750 GB Serial ATA Hard Drive
Integrated Intel Graphics Media Accelerator X4500 chipset
Integrated 7.1-channel High Definition audio
Integrated 10/100/1000 Gigabit Ethernet LAN
PCI Express 2.0 compliant
Multi-in-One Digital Media Card Reader
Supported Memory Cards:
CompactFlash (CF)
Micro Drive
Memory Stick (MS)
Memory Stick Pro (MS Pro)
Memory Stick Pro Duo (MS Pro Duo)
Memory Stick Duo (MS-Duo)
MultiMediaCard (MMC)
MultiMediaCard 4.0 (MMC 4.0)
Reduced Size MultiMediaCard 4.0 (RS-MMC 4.0)
Secure Digital (SD)
Secure Digital High Capacity (SDHC)
Expansion Slots:
Four (4) DIMM sockets (occupied)
One (1) PCI Express x16 slot
One (1) PCI Express x1 slot
Six (6) Serial ATA 3.0 Gb/s ports
Two (2) PCI slots
Front I/O Ports:
Three (3) Memory card slots
Two (2) USB 2.0 ports
One (1) Microphone In jack
One (1) Headphone In jack
Rear I/O Ports:
One (1) PS/2 port
Six (6) USB 2.0 ports
One (1) SPDIF out port
One (1) HDMI port
One (1) 15-pin VGA port
One (1) DVI-D (dual-link) port
One (1) RJ-45 Ethernet jack
Line in, line out, microphone jacks
Side, rear, c/sub audio jacks
Case Features:
Two (2) 5.25-inch external drive bays (one occupied)
Two (2) 3.5-inch internal drive bays (one occupied)
300-watt power supply (115V ~ 6A, 230V ~ 3A, 50/60 Hz)