Is it worth it? I guess that depends. In my mind there is no real replacement for an amp. As a guitarist I just have not able to make the transition to software modeling, maybe I'm just too old school. A mic properly placed, an amp dialed in well can't be duplicated by software especially when it comes to "playability." Stompboxes become an issue as most of them need a true amp load in order to work well. However software modeling is awfully close once a recording has been captured, so you might want to consider both. Take a DI of the guitar and send it to an amp as well, recording both. This will give you the ability to tweak to your heart's content at a later time. As far as software goes guitar rig is a good program.

No way I hell guitar rig will give you better sound, I've tried these things, incl. GTR 3 from Waves and whey don't come close to a decent amp mic-ed decently and not even decently just put a mic anywhere and it will sound better!