i have heard bad things about 01-05 civics. i've heard they're slow, and don't have that much potential.

 

7th gens are mainly about aesthetic if you want power get an EK either an SI or EX...something with VTEC

 

a 7th gen EX and EK(96-00) EX are going to be just about the same powerwise.
The 99-00 Si has 160hp stock. The 96-00 EX has 127hp stock. 01-05 EX also has 127hp stock.
All three have VTEC, but the 99-00 Si has "true" VTEC, since it's DOHC instead of the other engines' SOHC.
Really, the best thing in your price range that's stock is a 99-00 Si. Although you could find an already turbo'd civic for under $6,000... but what's the fun in that? All the work's already done, and the car is probably beat to hell.

 

Be prepared to get the Si stolen. I've heard too many horror stories.

I say buy a cheap EK and do all the work yourself, you'll get much more satisfaction out of it