Just in case anyone with an older system is wondering how well Skyrim runs on such, I'm happy to report that on mine, it's running surprisingly well. Specs are...

C2D 8500
4GB Dual-Channel RAM
512MB ATI Radeon 4870
500GB 5400RPM HDD
Sound Blaster X-Fi Extreme Music
Windows XP 32bit
32" HD TV

running the game at full rez 1080x1920
settings on HIGH

With Vanilla, I was averaging 50-60fps outside and 60fps inside (VSync)

After adding a few mods to brighten up the dull surroundings, I am now comfortable averaging 30-50fps outside and 50-60fps inside.

I've been playing for about a week and a half and have experienced no lag and only one crash.

Very happy that I don't have to upgrade my rig for now.