I really want build my own computer but I see that hp has a pretty good set up:

->Intel® Viiv Processor Technology with an Intel® Core 2 Quad Processor Q6600
-> 2.40GHz processor speed
2x4MB L2 Cache
-> 1066MHz Front Side Bus
-> 3072MB PC2-5300 DDR2 SDRAM memory (2x1024MB 2x512MB) (expandable to 8GB)
-> Memory Slots: 4 DIMM (240-pin, DDR2) (occupied
-> 500GB 7200RPM serial ATA hard drive
-> SuperMulti DVD burner with LightScribe Technology: 16x DVD±R, 8x DVD+RW, 6x DVD-RW, 8x DVD+R DL, 8x DVD-R DL, 12x DVD-RAM, 16x DVD-ROM, 40x CDR, 32x CDRW, 40x CD-ROM
-> NTSC TV tuner, over-the-air ATSC high-definition television tuner and FM tuner (antenna included)
-> High Definition Audio, 8 speaker configurable
-> NVIDIA GeForce 8400 GS graphics card with 256MB dedicated video memory, TV-out, DVI and HDMI capabilities, up to 1535MB Total Available Graphics Memory as allocated by Windows Vista


Since the computer has a 8400GS I wanted to know if I bought a 8800gt and a new 600 watt power supply if it would really work or is it hard to change these parts out on a prebuilt computer.

I know its worth it I just want to know if it is possible

You seem to know alot about this subject. I am also wondering if the hp psu could be swapped with the OCZ GameXStream 600w. I am just worried about the the size of the new psu and if it would fit in the case.

Here is the computer. http://www.samsclub.com/shopping/navigat...9414&pCatg=5816

I think that it would fit too but some power units are different sizes and I think that this case is seven inches wide. I am just not sure.