You can use .eps with GIMP, you just need a plugin.
Can't remember which or from where though.
Edit:
# I can't open PS and EPS files. Am I missing something?
# You need to install GhostScript to be able to read PostScript files with GIMP. GhostScript can be downloaded from
http://pages.cs.wisc.edu/~ghost/. After you install GhostScript, set the environment variable GS_PROG to the full path to gs.exe.