Zotac GT 520 is PCI-E not PCI.
I'd say...the days of AGP cards are over. Better build a new machine altogether.
no buddy - just check out the spec page - this is a PCI gfx card
ZOTAC GeForce GT 520 512MB 64-bit GDDR3 (810 MHz/1333 MHz) Graphics Cards [ZT-50610-10L]
@ OP - it would be best for you to opt for a new system - get
Athlon II X2 @ 250 @ 2.8k
Asus M5A78L-M LX @ 2.8k
2GB DDR3 Transcend/Kinston Ram @ 0.6k
after getting this you'll have ~2.5k in hand - save a little bit more and add a gpu later