Hi imper and Welcome to the Forum!! 
Any external hard drives I've used always just worked when I plugged them in... maybe Win 7 isn't detecting it because it doesn't have that specific model in it's library of devices..? Or maybe it can't find the right driver's to get the drive up and running... I'd do some searches on google first to see if anyone else is having a problem with that specific model..
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it sounds like a driver issue though... in which case you'd have to either search for a beta driver for Windows 7 for your external drive or try the newest Windows Vista driver for your drive and see if that works. If there are no Windows 7 drivers available for your drive yet and the newest Vista one doesn't work then you'll just have to wait until there is one released.. You have to remember Windows 7 is in BETA stages and as such there are going to be issues like this.. and unfortunately some aren't going to be able to be fixed until Windows 7 is further along in development..
Last edited by Radenight; 01-02-2009 at 04:54 PM.
Operating System Windows 7 Ultimate 64- Bit Edition
Computer Type Custom Build 6 of 6
CPU Type and Speed AMD Phenom II X4 965 (3.4GHZ) 4000MHz HT Quad-Core Socket AM3
Motherboard Chipset Asus Crosshair III Formula AMD 790FX Socket AM3
System Memory Type Corsair TR3X6G1600C8D Dominator - DDR3-1600:PC3 -12800 - 6GB - Non-ECC Unbuffered 240-Pin DIMM
Video Card Type and Speed Sapphire Radeon HD 5870 1GB PCI-Express (2.0)
Computer Monitor Samsung SyncMaster P2350 23" FULL 1080p HD LCD Monitor
Hard Drive (2) WD VelociRaptor 300GB 10000RPM 16MB Buffer: (2) WD Caviar 1.5TB "IntelliPower" 64MB Buffer
Optical Drives (2) LG 22x Super Multi Drives (SATA II) - Both with Lightscribe
Network Adapter Asus Crosshair III Formula Gigabit Ethernet Adapter
Anti-virus Software AVG Free Edition 9.0
Computer Skill Level Self-Taught Expert
Windows Experience Index 7.2