The reason 07 PC is the best PC version in a long time (and probably all round IMO) is because this year EA did actually go out and hire better help in Headgate Studios, who have been working on Tiger Woods PC for a while now. They clearly optimized the code for the PC as 06 and before was jittery frame rate wise even on the beastiest PC. That and the editing community anyway
The graphics aren't
technically better than the 360 - A helmet on the 360 has more polygons than an entire player model in the PC version and the textures are of low resolution, sometimes as low as 64x64 believe it or not. However, while it's not a technically better looking game, personally I prefer the more realistic models and movements on the PC, the 360 versions feels like it took a step back authenticity wise to me.
For Madden 08 PC, presuming they don't can the series on the PC, I kinda hope they don't port the new game over, but rather just give the current game a huge graphical overhaul for DX10 (or just true DX9, it is currently more DX8 than 9) and add whatever features 08 brings on the 360 (fingers crossed for some sort of gang tackling). I think EA should let Headgate Studios loose on Madden PC - let it become their pet project. I think they are more than skilled enough given the quality of 07 PC, which I doubt they had a whole lot of time on.