Although I admit there likely won't be any changes made to the 17 and 20" iMac lines we never know what Apple are going to release. Its their 30th anniverary and for their 20th they released something new and crazy, for all we know they might be releasing a 23" iMac, which could be very interesting for the OP if he's currently considering a 20" iMac. Its a long shot I know but this is probably the most unpredictable event in regards to new product releases for the last ten years. Wait, just in case. Its not long now!!