I use Bonsai (
www.natara.com) on my Windows PC which syncs very well with my Palm PDA. Very simple! Bonsai --> Palm PDA --> Bonsai.
I would use Omni Focus but it lacks some critical features. At some point though if those features are implemented, this is how I would do things if I decide to use Omni Focus on my Mac Book.
Omni Focus on Mac --> Take laptop with me :-)
or
Omni Focus on Mac --> Print out what I need :-)
The MacWorld expo starts tomorrow and there has been talk of an ultra-portable Mac laptop being announced. If so, that might help -- just take your laptop with you, esp. if its a good ultra portable Mac laptop.