I'm in the middle of downloading Yellow Dog Linux as we speak. There is a media player which will play DiVX and I'm sure there will be an app to play my PAL DVD's too. This woudl solve all my problems and make the PS3 do everything I want it too.
With regards to F1, I used to love the Geoff Crammond games for the PC but they arent releasing any more as far as I'm aware so the only decent F1 games left are the PS ones. This version has more tweaks as far as I can see so that you can make it much more like a sim than the previous arcadey style versions. Other than that you could get yourself a cheap pcopy of Geoff Crammonds GP4 from fleabay, there are huge communities of modders who always update the car models and tracks etc to the latest season and considering it's a good few years old you wouldn't need the latest GFX card to run it. Obviousley I'm assuming you have a PC but I suppose you could be typing this on any number of gadgets nowadays.
Why dont you look at titles due to be released on both platforms, cross off any you can get for the PC, if you have a gaming rig, and then think about which ones you most want to play from each. Then go for the one with the most titles you really want.