As long as the ratio of the resolution is the same its pretty easy...
1920/1080 = 1.77
1440/900 = 1.6 (not so much different)
1680/1050 = 1.6 (same as above)
1280/1024 = 1.25 <-- this one needs cropping
ahh alright so the 1920/1080 can be easily scaled down to 1366/768. Thanks!