Starting Fresh

Hey all-

I have a 15" MBP i7 running 10.6.8. This is my 3rd mac laptop. Here's my issue:

I recently played with a friends MBP (same model) and was immediately shocked by how much "better" it ran. When I mentioned this, she asked me how I transferred stuff from my previous macs onto my new ones. Therein lies the difference: She meticulously picks and chooses specific files, whereas I dump everything to time machine and do a restore. She claims that's the root of my problem.

SO...I've been going through my files to organize things, and I've noticed theres a ton of "crap". This includes "junk" files, old .zip's, partial folders from long deleted programs, etc: vestigial remnants of macs long past.

I'm fixing to update to Lion, but before I do that, I would like to turn back time on my computer and start fresh. Here's my point: I have a sick feeling that the only way to fix this is to dump everything to an external HD, do a completely clean OS X install, then slowly and carefully, pick and choose what to put back on.

Long story short, does anyone know a more efficient way to do this?

Thanks folks