I was just about to recommend the Ultra Sport

It's the best plane ever put in a box! And it comes in a 40 or 60 size:

http://www3.towerhobbies.com/cgi-bin...?&I=LXJ583&P=7

http://www3.towerhobbies.com/cgi-bin...?&I=LXJ584&P=7

However, although the manual is excellent and it guides you step-by-step, it may not be the best "First" building experience. There is a good deal of sanding involved (But you CAN omit the wing fillets which can be a pain to do for the novice builder)

Here is a thread I started on MY Ultra Sport 60 build:

http://www.rcuniverse.com/forum/m_6822225/tm.htm