that's what i'd like too. an option to either define a custom window size, or one that'll display the graphics in 1:1 size, regardless of what they are, resizing the window automatically as needed.
in the meantime, @genius: try using this program.
Tarma Installer, Tarma ExpertInstall and Tarma QuickInstall
i tested it and it works wonders. you just have to remember to include the border size into the size settings. set it to resize other window class, then select the pcsx2 entry. for me it starts with "afx: 0c800000"