Iirc you still need to start FH0.7 in admin mode, which you can do by going to the preferences on the link and then choosing "run as admin".
Other than that you have to disable punkbuster since it doesn't support the Win98 compatibility (same procedure as with admin mode) uder win7.
Also be sure NOT to install BF42/FH0.7 in the program files/ folder (both x86 and the normal one should you use a 64bit version of win7) as win7 is a bit tricky with files being changed in that folder.
Deactivating you user access control in Win7 also helps.