I've only tested far cry demo and it seemed to be working well with 12.8, no glitches of the kind to report, nothing funny going on with zooming, I had some oddities that didn't cause visual glitches (changing settings on the menu initially gave me a gray screen, not a driver crash just the game stuck in there, and required me to restart the game, but at least it changed the settings, and when I started to take screenshots with afterburner "system" decided to use 50% of the CPU, but the game was still running OK)
but from FC demo to fully patched FC they've changed things quite a bit (I think the demo runs in SM 2.0 at best for example), still it might be another bug introduced by a newer driver version,
as for the comparison with Nvidia, well I'm not claiming the GCN 1.0 cards are better on XP, but I think with the older drivers I'm seeing it as a viable option,
I did find Mafia a little too slow for my taste (it seems like the e7300 was struggling), but at least it didn't have the shadows glitch that I have with my FX 5900 with the drivers I tested (45.x and 53.03 so far), the shadows also glitched on windows 10 with the Radeon with the newer driver, but not on XP with 12.8, but I want to test Mafia more because the performance didn't make a lot of sense; basically I'm seeing potentially lower framerate on bad spots with the e7300+7850 than I saw with the FX 5900 with a P4 s478 3GHz and it looks very CPU bound...
with the i5 on 10 it runs massively faster, even with me forcing the i5 (which is a sandy bridge) to 1.6GHz (on 10) it was still over twice the framerate of the e7300 (with XP), when I have some time for this it's probably a good idea to run XP on the i5 to see how Mafia behaves,
EDIT: oh yes, there is something going on with Mafia, I swapped the HD 7850 for an HD 4670 DDR2 (12.8GB/s ram!) and it's night and day, I tested this quite a bit and it's very consistent, the 7850 (with cat 12.😎 runs very often at 40s touching 20 in heavy action, be it 640x480 or higher res... the same exact PC with the 4670 = 63FPS pretty much locked all the time....
still, it looks the same on both, no shadow glitch at least I suppose.
there are some other disappointing results comparing the two, but nothing like Mafia so far,
still I had NFS Porsche run fine in DX7 with the 7850 and glitch the texts with the 4670 with 2 different drivers (9.3, 13.4) 🤣
driver 13.9 fixed the performance issues and high CPU usage in Mafia!
but... it added some glitching on NFSHP2 demo, basically some "lines" on the car reflections, and the driver of the ferrari is all gray.
still, I tried 9.1, 9.3 and 13.4 and the fonts on NFS Porsche are always glitched with the HD 4670,
and with the HD 7850 with both 12.8 and 13.9 the fonts are fine!