iPod touch 2nd gen software downgrade?

I have an iPod touch 2nd gen. 8GB. It's current version is 4.2.1. I upgraded using my brother's mac. My mac can no longer update it's own software therefore not allowing me to update my iTunes to iTunes 10. I was wondering if there is a way for me to down grade my iPod so that I can use it on my own computer. I have already tried downloading iTunes 10, but can not run the program because of my computer's software being so far behind. I do not want to have to purchase another computer, I just want to know if it's possible to downgrade my iPod touch. If anyone has possible solutions it would be greatly appreciated. Thanks!