Trying to upgrade my video driver (radeon X1600) - daunting isn't the word!

Question

Silly me sprung for a 6-month subscription to a video game I'm enjoying on the Windows side of my partitioned iMac, and of course that caused the developers to release a patch that makes my video driver immediately useless. Game crashes at startup and unfortunately, it can't be worked around. I'm not overly comfortable poking around in the insides of Windows machines... after hours of research I downloaded the AMD installation app to upgrade my Radeon X1600 to the Catalyst Display Driver vsn. 10.2. After a few failed attempts, it gave me an 'Installation complete' message, but after restarting I still have the tired old X1600 installed (that's what the DxDiag report says, anyway.)
Not familiar enough with this sort of thing to want to start opening folders and rummaging; if anyone out there can give me some pointers I'd be eternally grateful; should you find yourself attacked by any mythological creatures, give a yell and I promise to come rescue you!
Here's what I've tried:
Download page:
http://support.amd.com/us/gpudownload/windows/10-2/Pages/radeonaiw_xp.aspx?&lang =English
Installation Instructions:
http://support.amd.com/us/kbarticles/Pages/GraphicsDriverInstallationInstruction forMicrosoftWindows7.aspx

Answer 1

I'd take the link  above (there are others too) and create a list  of steps and run through that in your mind - it is unique to Macs.
You'll be better for it if you just uninstall the program for AMD and Nvidia / uninstall the driver in Device Manager.
From there you have a clean slate for AMD driver. Some have used Driver Sweeper. But it really isn't or shouldn't be a nightmare - more like you are growing new gray cells and out of the slumber of not having to know or deal with how to get over the obstacles.
Windows on Mac is not 100%. There are hurdles and road blocks that no PC and no Mac using OS X need contend with.
Those threads have 10 people's inputs, opinion, what they did but you don't come away with a cookbook or recipe.
Some people did though and posted theirs. The good news is that it has gotten better. In the past you actually needed to go to Laptop2Go for modified drivers to use because the standard drivers and Apple's didn't.
Your two links, one is old out of date for XP, not 7. The other is not the current driver download page. Those set you on a different route.
Installing only happens after you remove the Apple set of roadbocks. Programs and Device Manager. Spriinkle with touch of 'salt' (Driver Sweeper 3.2) that removes registry keys and files.
Oh... as I did through AMD, it seems your X1600 is almost unsupported now.
I am choosing Mac graphics and Boot Camp as I could not find X1600 on its own:
Apple Boot Camp Windows 7 and Windows Vista Software Graphics Drivers
http://support.amd.com/us/gpudownload/Pages/bootcamp-win7.aspx
The driver is over a year old.
https://a248.e.akamai.net/f/674/9206/0/www2.ati.com/drivers/8.812-110104a-112011 C-Apple.4-Win7Vista.zip