I filled up my 250 gig and just purchased a second external hard drive. The one I have now shows up as "drive F" ... my question is ... do I need to disconnect and replace the current external hard drive, or will my computer be able to handle another? I still have several vacant 2.0 USB ports. Thank you for any advice. (Dell 4550 / pentium 4 2.53 Ghz / processor speed 2.46 Ghz / 256 ram / XP / operating system 5.1.2600)