I don't have enough knowledge to make any suggestions, but I don't think it's so bad having only two channels for drums. It forces you to spend the time up front to get it right in the first place. Have you read the recorderman drum thread? It's got some pretty cool info about micing a drumset with as little as 2 mics. Just do a search for recorderman.

Yea that could wrk but my problem is that i have several dynamic mics which i couldnt really use as overheads, i guess a possible solution would be to buy some condensor mics, but i would prefer being able to use more than two mics

Sorry, don't know what an MBox is but any PA mixer has line outs. Just hook them to the MBox and mix-down through the PA. Radio Shack has one for < 100 dollars, I think it's four channels. I saw a complete PA at Sam Ashes last year that sounded great for 250.00,
and they even through in a flat-top guitar that was playable.

if the mbox has 2 xlr inputs, you can buy any mixer that has xlr or 1/4" outputs and run the cables into the inputs on your mbox. you could find something by behringer for around $150 that'll run 6 or 8 mics into it.