The athlon 64 3200 was released in 2003: do you know if you've got an AGP or PCI-E graphics card?
I found this discussion about 1080p playback:
http://www.videohelp.com/forum/archive/what-should-i-update-to-play-1080p-gpu-or-cpu-t360761.html This discussion was in 2008, back then it seems an 8600 GT or even an up-to-date on-board graphics processor could handle HD 1920 graphics. Blueray requires an HDCP graphic card and virtually all PCI-E graphics cards support HDCP. The cheapest card available to me is an EVGA Geforce G210 (589Mhz), 512MB DDR2 priced @ 55 Australian Dollars which is about 20 quid.
http://www.evga.com/products/moreinfo.asp?pn=512-P3-1212-LR This of couse pre-supposes that you have 1) a PCI-E slot, 2) 300 Watt power supply and 3) a CPU that can handle it.
