I am using Windows 7 Home Premium on an even older system:
1. CPU: AMD Athlon XP2800+ 2.2 GHz (Socket A)
2. MBD: Asus A7N8X-E Deluxe
3. RAM: DDR 2x1GB
4. GPU: Nvidia GeForce FX5900
I would not have gone out and bought a copy of Windows 7 just for this computer but I already had a copy of Windows 7 Home Premium Family Pack. I had only used 2 of the 3 allowed installations so I had one available to use.
Back in 2006 I had tried Windows Vista RC2 on it but it I was dissapointed with it. Not only was it slow but driver support was rather lacking. Windows 7 works better than Vista ever had. My only problem was with the wireless network adapter. The Linksys WMP54G Wireless-G PCI Adapter Windows XP driver does not work with Windows 7. I did manage to find a driver from the manufacturer of the chip on the card that works with Windows 7.
Gigabyte GA-990FXA-UD3 | AMD FX-8350 | Corsair H60 Cooler | GSkill RipjawsX (2x4GB) | ASUS GeForce GTX 560 | WD Caviar Blue 1TB | Seagate 750GB | ASUS 24X DVD/RW| Windows 7 Ultimate 64-bit
ASUS M4N82 Deluxe | AMD Phenom II X4 960T | Corsair XMS2(2x2GB) | PNY GeForce GTS 250 (1GB) | Seagate 300GB | Maxtor 200GB/250GB | Memorex 20X DVD/RW | Windows 7 Home Premium 32-bit