Hi there, Here is the iMac that I just bought: http://cgi.ebay.co.uk/ws/eBayISAPI....91488&ssPageName=STRK:MEWNX:IT#ht_1063wt_1139 I want to upgrade a few things on it, like HDD etc... It comes with os 9.2 and 10.1 at the same time - 1. how is this possible? 2. Does having 2 os's slow the computer down? I have Tiger CD's and Mac OS 9.1 CD's - could I put these 2 on the iMac G3? Here is the long list of questions! 1. Will this hard drive work: http://cgi.ebay.co.uk/ws/eBayISAPI....077755&ssPageName=STRK:MEWAX:IT#ht_2814wt_914 2. What is the max ram? 3. What DVD drive would work? 3. Could I fit a G4 Processor and motherboard? 4. What is over clocking and how does it work? 5. What is the best processor I could fit it? Thankyou very much! John.