http://www.usbgear.com/computer_cable_details.cfm?sku=USBG-232&cats=106&catid=482%2C1303%2C199%2C461%2C106%2C1009%2C601It is amazing how many problems people have with this. I left the link for the above adapter, that worked for me on XP and Windows 7. All $25 shipped. No headaches. Stop driving yourself crazy.
BTW, the above adapter is 1 foot long, so you will need a 10ft serial extension. I got one on ebay for like $6 shipped.