Welcome to the forums!
Slug indeed moved the post to the right place, as this subforum is where you'll find all the info you need.
To use 1.6 on the I7500, you have two options: you can either use a firmware released by Samsung (it's not official, but it works). To do so you'll have to use Odin, a software you'll need on your computer.
You could also use Galaxo (and I recommend this option). It's a custom android 1.6 ROM based on the unofficial Samsung firmware. It's considered the "best" firmware for the Galaxy.
You might also like to hear that there is an Android 2.1 ROM available. A few things don't work though, such as the camera. A Froyo (Android 2.2) ROM should be available soon too. This project is called GAOSP.
Whatever option you chose, read the list of tutorials (a stickied thread) and you'll find info on how to do it. If you got any issues, ask for help or PM me if you want me to explain it personally.