You cannot run Serial ATA to usb!!!!! Sata, at the present time must be Modo direct or cabled via a PCI SATA controller. The solution is a motherboard with on-board SATA interface. With the adapter, your Cmos recognizes the drive. Since you have it connected to a PCI SATA card you have an inherent transfer rate/bandwidth issue here and not dirve size. The problem with these cards, not being mobo integrated, is that they suck up a whole bunch of bandwidth and if the data transter is too big your Sata drive lags and then hangs up. Again, it's not the size of the drive that is the problem but the PCI cards transfer rate. New mobo dude!
Edit: You buy a new mobo and the 300 gig SATA becomes your primary master and your puter will speed up a bit!!!
Edit #2: What pin configuration on the 1.7 gig cPU. Intel or AMD? Becasue if it's an older CPU it might be a little harder to find a board with SATA. Post the CPU and pin config. anbd I'll find out for you.
Noli Nothis Permittere Te Terere!!
EVGA 680i, Dual EVGA 8800GT'S (650/950), 4 gigs OCZ DDR2 1066, Intel Q9450 at 3.8 Ghz, Koolance Water Cooled, Dual Plextor16x DL DVD+/-RW. Dual WD 250gb 16mb Cache Sata 3.0. 3DMark06 score = 19,168.