The old rig:
9800 Pro 256MB
1 GB Corsiar PC(3200?)
2.

P4 OC'd to 3.0
2x 80GB SATA Drives in RAID0
Creative Audigy 2 ZS
XP Pro SP2
That system always ran the game fine (except for a few of the flakey betas) at 1280*960 with 2x AA.
New Rig:
7950 GX2 1GB
Core 2 Duo E6600 (2.4GHz)
2 GB Corsiar XMS2 DDR2-800 (PC6400)
Same HDD setup, just updated to 3.0GB/s SATA drives
XP Pro SP2
I ripped the Audigy 2 ZS out the other night since Creative drivers still blow. I was having HORRIBLE crashing issues in Oblivion with that damn card which have ALL gone away now. Now I'm on the onboard Realtek ALC883 and I'll be damned, it sounds better!
Haven't yet had a chance to see what GC2 will take, right now I'm running at 1600*1200 with 16x AF and 4x AA (though I'm sure the AA can go higher). I've only had the system a couple of weeks now, so it's hard to really comment on GC2 stability. I've only had one issue and that was a CTD when I hit ctrl+N. Haven't been able to reproduce it and I've had no issues with the 1.3b3x build either.
To the person with the Live! card, well, I'm sorry. I had that card too and those drivers were even worse than the Audigy ones. If you ever encounter any crashing issues start by disabling the card in the hardware page.