educate me

The better the cartridge, the better the overall sound. There is nothing in a stereo system that is an ultimate limiting factor. Every piece in the chain contributes. Even if you have Bose speakers, you will hear better sound from a better cartridge. The choice between a higher output over a lower output cartridge is determined by the ability of the phono stage to bring the level high enough for the system to perform to its abilities. There are some great high output cartridges that beat the pants over lower output cartridges, however, they cost more. Buy the best cartridge you can afford that works with your system. This advice is true for every component in your system. There are some components that perform better than others in their price range, and the fun is to select the best bang for the buck.

Even if you have Bose speakers, you will hear better sound from a better cartridge.

This is true, I think. One seriously interesting way to spend a budget is to put 80% of it into the source, then upgrade downstream as savings permit.

So I agree it might make some sense to listen to a great cartridge with Brand X speakers, if you hoped to upgrade eventually. The upgrade would only let you hear more of what the cartridge was already doing (but inaudibly) with those Brand X speakers. You have the highest-resolution component upstream. All systems should be balanced like this.

That's why it doesn't make sense to use a premium cartridge with an entry-level arm (and/or turntable). To put it one way, the cartridge's great resolution would let you hear the arm's limits much more clearly. Put another way, you would not be getting the best performance for the money you spent on the cartridge; whereas if you spent the money on upgrading the arm, you would then be getting more out of the cart.

went with a Rega P3 wasn't even thinking that way then bang, there she was, 5 yrs old from a fellow Agoner wih a 300 arm and a Ortofon X-3 cart.
Hope I did well, thanks for all the help.

okay, I lied, cancelled the P3 when I found out to adjust the VTA I had to use shims, should have done my homework better. Between a Music Hall MMF5.1 and a Pro-ject Xpression, think I like the arm on the pro-ject better and its $100 cheaper but the cartridge sucks, any ideas for a good (under $200) cartridge?