Grab your entire settings folder.
Typically c:\program files\HTC\Aces High II\settings.
While your at it, if you have any custom gun sights grab the sights folder.
Grab the AHIIterr folder to save you downloading terrains again. And skins of course if you had the skins downloaded.
Take all of these, put em in a folder like AHbackup, and copy it where you need it.
While your at it burn it all to a CD/dvd, put a copy on a flashdrive, wifes computer, work computer, laptop, or anywhere else you can think of to back it up.
Settings folder will get you your head positions, username & password, video setup, all the config files AH uses. BTW you might want to delete or rename video if on new computer.