Tutu is a program that allows you to run BG1 on the BG2 engine. Needless to say, you must own both BG1 AND BG2 in order for it to work.
A massive positive for Tutu is that its a very small download and makes the BG1 experience far more enjoyable.
For more information visit:
http://www.pocketplane.net/mambo/ind...=143&Itemid=98