Windows XP SP2 installation problem

I've tried to install the Windows XP Service Pack 2 twice (once with CD) and both times on reboot after installation I get a blank screen with only the background. No icons, and no pointer, no start, or anything. I was advised to try right-clicking on the screen to bring it all back up but nothing happened. Tried System Recovery once, and that's too much to go through again to be back at point one. Without SP2 I can't get some security downloads and they're dropping support for SP-1 soon.
I have an HP a450n, 3GHZ intel pentium processor w/hyper-thread, 512 MB SDRam, 160 GB 7200 RPM Ultra DMA hard drive (less than one gig used up), NVidia GeForce FX 5200 ASD 8X graphics card x 128 DDR video memory, TV out + DVI support

 

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http://forums.majorgeeks.com/showthread.php?p=829161&posted=1#post829161