my chainring is slightly bent, time for a replacement. right now i'm running 46x17, thinking this might be a good time to up it to 48. i know i need a five bolt, but what else do i need to know/measure? what's BCD? what chainring would you recommend on a pretty tight budget?

If it's just bent, just bend it back. Details on Sheldonbrown.com, along with how-to's on measuring BCD. Rocket rings are fine for really pinching $, beyond that you need to know the BCD as not all rings come in all sizes.

well, i also suspect the one of the stack bolt threads is stripped as well, there's one that just wont seem to tighten all the way like the rest of them. this may be why i assumed it was bent. either way...

Get new bolts, or the chainring will probably fail at the worst possible moment.

To find BCD, measure (in mm) the distance between the center of two adjacent bolts and multiply by 1.7013.