Which graphic card can I upgrade to?? Help please

My computer's around 5-6 years old and it can't handle some things so i'm trying to see if I can upgrade the graphic card...help is appreciated!


APPROXIMATE PURCHASE DATE: Anytime BUDGET RANGE: $0-300

USAGE FROM MOST TO LEAST IMPORTANT: Movies, light gaming, video editing, browsing

CURRENT GPU AND POWER SUPPLY: ATI Radeon x1200, 350W output
OTHER RELEVANT SYSTEM SPECS: AMD Athlon (tm) 64 X2 Dual Core Processor 5000+ 2.6GHz
3.00GB RAM
64 bit OS
M2A-VM 1.XX Motherboard

PREFERRED WEBSITE(S) FOR PARTS: NCIX COUNTRY OF ORIGIN: Canada

PARTS PREFERENCES: N/A

MONITOR RESOLUTION: 1280x1024

ADDITIONAL COMMENTS: Won't be using it for hardcore gaming like I said but I would like it to run the occasional light games smoothly. Right now, my computer can't even run simple games like Amnesia or Slender