Do you have the restore discs? has it been restored using these? if you don’t know try fn + f5 do you get a brightness control appear on the screen?
If yes I’m not sure why you can’t select the correct resolution. If no it looks like someone has just installed Xp from a windows CD and not by using the restore DVD’s. The restore discs contain all the specific extra drivers and files for TR specific function. You can get all this manually but it’s a lot of faffing around
I can’t help on the DVD’s because TR5 is region specific and Uk (my location) is TR5mp these wont work on TR5C see this PDF file for more details on the region your TR5 is for:-
http://www.zfz.com/pictures/vaio/files/tr5.pdf
either way you can get a update graphics driver, I post back with link