I have a two-pronged solution for this:
1. if you have a recent, clean Time Machine backup: restore everything from that backup
2. if you have been (un)installing a bunch of crap that might have changed system files, if you felt sluggish or there could be any problems with OS X in the old system: do a fresh install of OS X from the install DVD or your MBP DVD (whichever is newer 1st*)**, then do a complete Software Update, (reinstall /Applications manually), & restore User files & settings from Time Machine, repair permissions
*if the MBP DVD is newer, that is the obvious choice. If the OS DVD is newer, I would lean toward installing the fresh new OS, then install only the additional software packages you're interested in, such as iLife, from the MBP DVD
**make note of any software you might need to reinstall manually as it makes system level changes. For example, tun/tap for openvpn, or printer drivers that came with your printer (not available by default OS X install), or any other software that requires a reboot (which is actually the kind of software I try to avoid whenever possible).