If you wanna run vista on <512 mb of ram, you may install windows vista starter, or at least, turn off the Windows defender, it will be free much resource for you , ignore my bad english, i'm a student from indonesian. My Comp : Pentium !!!/550 Mhz 256 MB of RAM Matrox MGA G200 PCI (8mb) Sound Blaster Live ! HDD 20 + 4.3 GB (The 4.3 GB is OEM) Windows Vista Starter, and Home Premium (Just For Testing)