Ok well i've look in maple places on how to run maplestory in window mode but no answers
but here is a cheap guide
1st change the compatibility mode to Windows Vista
i have run 640 x 480 checked off so u can try that 2
2nd download msvcp71.dll from here
msvcp71.dll free download - DLL-files.com
3rd put msvcp71.dll in maplestory folder
and run maple

srry if its messy im in a rush D: