I also have an AGP 4x slot. Its not worht it for me to upgrade and get either a low priced video card to fit into my 4x slot and then have to upgrade again in a year. or get a high priced card and stick it in my 4x slot and not have it work to its potential. Whats the point of paying all that money. My solution, brand new system for a few bucks more than it woulda cost me to upgrade everything on my old pc, then i have 2 pc's and one that'll be a strong competitor for the next 3yrs.
AMD Athlon 64 3500+ [939 Socket] W/ ASUS \"A8N-SLI Deluxe\" nForce4 SLI Chipset PCIe Motherboard
Kingston 1024 MB [512MB X2] DDR-400 PC3200 Memory
MSI Nvidia GeForce 6600GT 128MB DDR3 128-bit PCIe
Western Digital 160 GB 7200 RPM 8MB Cache SATA Hard Drive + WD 120GB 7200 RPM IDE HDD
LG Dual Format/Double Layer 16X DVD±R/±RW + CD-R/RW Drive