don't replace the piston rings!!!! unless you plan on honing your cylinder. or at least rehashing it. if you just drop new rings in, they'll never break in properly and you'll prob have sh*ttier compression than you do now.
not only that, but if you do hone the cylinder, you're increasing the gap between cylinder and piston which increases piston flap and you're just asking to have your skirt chewed up (believe me i learned the hard way).
don't replace the rings unless you need to (compression check it) and when you do, don't just throw new rings in there, you want to bore and hone and replace the piston w/ an overbore.