Villian is semi-loose from the hands I've seen him play.

***** Hand History for Game 2133430647 *****
$25 NL Hold'em - Tuesday, May 31, 08:47:35 EDT 2005
Table Table 36663 (Real Money)
Seat 2 is the button
Total number of players : 9
Seat 1: CO ( $46.26 )
Seat 2: BUTTON( $24.65 )
Seat 3: SB( $28.85 )
Seat 4: BB ( $33.9 )
Seat 6: Villain ( $22.85 )
Seat 7: Hero ( $51.21 )
Seat 10: MP1 ( $21.3 )
Seat 9: MP2 ( $35.2 )
Seat 8: MP3 ( $4.75 )
SB posts small blind [$0.10].
BB posts big blind [$0.25].
** Dealing down cards **
Dealt to weezey401 [ ]
Villain calls [$0.25].
Hero raises [$1].
MP1 folds.
MP2 folds.
MP3 folds.
CO folds.
BUTTON calls [$1].
SB folds.
BB folds.
Villian calls [$0.75].
** Dealing Flop ** [ , , ]
Villian bets [$2].
Hero raises [$5].
BUTTON folds.
Villian is all-In.
Hero folds.

Villian does not show cards.
Villian wins $29.55

At that point I had him pegged for 2 pair or a set. What do you guys think?

He's betting like $19 into a $9 pot... I certainly wouldn't call w/ TPTK... He could have anything from a flush draw (maybe , since you said he was loose), to 2pr ( a LOT of loose players like playing Aanything...) or a set... 2 out of 3 of those you lose... I usually like to get all my money in where I feel I'm a pretty significant favorite, and I can't see how you'd think that in this case... If he's loose, you'll get better chances to bust him, and I'd fold...

I'm gonna go ahead and disagree with MVP here. The guy calls a 4xBB raise, give him credit for something better than A2 or A3 although this may not necessarily be the case. PLENTY of people at NL25 would push all in here wtih ANY ace, in fact, I'd say most. So you're ahead of any ace except A2 or A3, and 22 and 33, in all honesty, I don't see myself folding here. Then again, I'm an idiot, so maybe someone else could provide more insight.