If you use XP go to Micro$oft's web site and do a search for Powertoys. Download the image resizer. After you install it go to whatever you want to use for your avitar, right click, and choose Resize Image from the menu. That will pop up another window. It will show you four default sizes and there will also be an Advanced button. Click it and it will expand the window to show you custom sizing and also a box to check if you want to resize the original picture instead of creating a new one. In the custom size put in 150x150, decide if you want it as a copy or resize the original, and click OK.