If you could post what kind of things you intend to do with it, etc.. i.e, if its just email, web, work music and movies or some photoshop, video editing, data acquisition, analysis, encoding.. if you have any windows related programs (like for work, or for specific tasks.. even though there's a mac equivalent for just about anything.. and then some.. ). You'll get plety of thoughts as to what to buy and I've seen mostly good advice around here on this stuff. The aren't TOO many options because just a few cover it all.. the mini, imac, mac pro, macbook macbook pro.. older ones, refurbished ones, etc... budget?
I'm personally using a 2.33 ghz core2duo macbook pro with 2gb of ram and its been smooth sailing since day one

My lady has a mac mini which is good for what she does.. I've got an old ibook 466mhz with 512mb ram around the house which is great for email, web, music, movies(just) and online poker

.. so visitors dont need to use mine. its running the latest os x 10.4 and its great.. so it all really depends what you want to do with it, and where.. let us know.