Hi, I currently have 2 HDD's 1 - Western Digital 640 GB (SATA), partitioned into 450 GB and 190 GB 2 - Seagete 160 GB (IDE), paritioned into 100 GB and 60 GB When I installed windows 7 (fresh install), all four partitions were recognized properly. Though the drive letter assignment was a little weird, I left it as is since that was the default assignment. WD 190 - C: WD 450 - F: SG 60 - D: SG 100 - E: Now I took out the Seagate Drive and placed it in an external enclosure. When I plug in the external casing to the USB port, the installation would take a very long time, and when I go to Explorer and go inside the drive, explorer would crash. I tried this on my other computer running win XP and it loaded fine. I also tried it with my sister's laptop also running Win7, initially it took a long time to install, but after that, it also loaded properly. Is it possible that the problem is because the harddrive was there when I installed win7, then when I removed it, there was some sort of problem with the mappings or something (sorry about this, I'm not familiar with harddrive mappings/disk management, I'm just guessing that it could possibly be the cause) My PC's specs: Win7 Desktop - E5200 (2.5GHz), 2 GB DDR2 Ram, P5QL-Pro (P43 Chipset) Win XP Desktop - Pentium 3 (733), 512MB Ram, no idea about the motherboard. hehe Win7 Laptop - T4200 (2.0 GHz I think), 1GB Ram Thanks!