Looking to upgrade my graphic card one last time.

I wouldnt know whether you just like ATI Graphics cards, or it was recommended for you. But I would still give you my straight forward advice, and this is : Go for NVIDIA Ge-FORCE graphics cards. Trust me, you would thank me for it later.
I didnt want to recommend a specific model for you though, because of our difference in country locations, but just try and get a high memory (like 256MB and above), NVidia Graphics card that is compatible with your system. Also check out the available slot on your system that you will use for it first before you go (So that you wont go and get an AGP slot card when you have just an open PCI Slot). I'm telling you this because I've used A LOT of graphics cards also (Over 10 years now)! and I've come to that conclusion that NVIDIA makes the best graphics card.
Hope this helps you out.
Goodluck!

Here is a link comparing these 2 cards:
http://www.gpureview.com/show_cards.php?card1=523&card2=458

As you see, not much difference between both cards, however the RADEON X1650 PRO 512 AGP 8X seems to be a better performer than the RADEON HD2600 PRO 512 AGP 8X