WinRar 3.0 is the most used format these days,
WinAce 2.0 is a close second. I prefer WinRar 3.0 personally. And the fact that you've got almost a 10:1 compression ratio, has probably everything to do with large amounts of zeroes in the executable you mention. This is much better compressable than a normal executable, and this executable probably got this way by removing the copy protection and putting zeroes in it's place. Other crackers just rip the copy protection out and make the executable smaller, a copy protection like safedisc 2 can take up to 2 Mb in the executable and a cracked exe can thus be 2Mb smaller. Normal compression ratio for an executable is anything between 2:1 and 1:1. So don't expect any great decreases in filesize with WinRar, although you can win 10-20% in comparison to the old Winzip format.