Don't expect much of a lifespan on the average USB flash drive. They aren't made for heavy writing and Windows writes a lot to disk during normal operation (swap file). If you want to try this, I'd try a USB harddrive instead of a flash drive, or get a higher end SSD.
If you need storage, I'd suggest to get a 2900 instead of a 2950 as this unit was available with 2+8 (3.5") drive bays; 2 in the 5.25" bays (this bay could also hold a tape drive) and then 8 bays together for 3.5" drives.