Yesterday, I bought a new HITACHI 500GB 5400RPM 2.5" MOBILE SATA (HTS545050A7E380) hard drive for my Dell XPS M1330. When I remove the stock drive and replaced it with the newly bought drive, the drive is not detected and it was not showing in the BIOS. The stock drive was a Western Digital 250 GB. I tried plugging it in my desktop and I managed to install Windows 7 on it but when I plugged it in again to the laptop, its still undetected. I don't have anymore ideas on how to fix this and just thinking on returning the drive and get it replaced with another brand instead. Thanks!