Setting up mythTV for a Sony KP57WV600 (modelines?)

Hey guys, I'm interested in getting started with my own PVR system via mythTV. I've been doing quite a bit of reading on here and elsewhere. One thing I will probably need some guidance on, for which I can't seem to find info on anywhere, is regarding setting modelines to avoid the "overscan" problem for my TV. I have a Sony KP57WV600 16:9 tv that I'd like to test on. Is there any way for me to find out what resolution and modelines are optimal for my TV? I have yet to make any purchases towards my PVR because I want to get a good grasp of what this whole process will entail b4 I make the plunge. So, I'm very flexible in the help and guidance that you can send my way. Are there any general guides regarding setting modelines that are out there? And does setting my modelines also require tinkering with the xorg.conf file? Thanks in advance!