Here is a good list of entry level planes:

http://www.rcuniverse.com/forum/m_4537845/tm.htm

Even though you have some helicopter experience that will probably reduce your learning time, I'd still recomend a trainer type airplane to start. You just need to decide which trainer and whether you want a kit, ARF or RTF. Once your comfortable with the trainer, you can move on to other, more interesting planes.

Also, join the AMA if you're not already a member and find a local club if you don't already belong to one. I could have cut my learning time in half if I'd just done those things in the first place.