AFAIK Laplink still supports old OS's. That is its very market. People who are upgrading. I think it supports serial ports and parallel ports as well as USB which you might not have.

Invest in the Laplink just for the transfer. You might be able to get a USB HDD box that can handle your HDD but it may be the wrong speed and getting the right one is a minefield. The Laplink looks to be the best way. You only need your own data, you should have the disks for the software you are using, and it will most likely work on XP/Vista/Win7. Certainly I can vouch for XP on all apps I have transferred over eg Morph Studio which was free 10 years ago and few products can match it that I have trialed..