Originally posted by rek
There shouldn't be a problem upgrading the group, though I'm not sure if space between the dropouts is an issue with MTBs if you want to upgrade to 9 speed..
The frame should have a headshok compatible head tube (it'll be really big compared to other MTB head tubes if so); so you should be able to put a lock-out headshok fork into it (along with a new headset and stem to suit.)