is this it? i suggest just taking all your upgraded working components and getting your gf a new bike. maybe a women specific bike. it will feel so much more comfortable on her and the components will stop breaking like they did on this MG.
bring it into the bike shop, they will help you easily determine what fork you need. if you purchase a fork from them, they will help you install it for free. if u buy the fork separate, they will charge you $35-50 to install the fork.
if you're low on cash u just gotta save, its a tough economy. ... or make more of it.