I use a PC at work and a Mac at home...
IBM T41 is my laptop at work and I have to say that it's pretty nice. I've used Compaqs, Dells and IBMs and have to say that the IBMs win hands-down (I've had a couple)...
As for Macs, I have a 2 year old iBook which is now my wifes and i have a brand new 15" Powerbook. Love them both. One mouse button is no problem (CTRL + Click is the equivalent of right clicking or if you use an external two button mouse you can right click til your heart's content)... the built in software that comes with the Macs is great (safari, itunes, iphoto, imovie, iEtc). Everything you need is there (other than your word processing app which you would have to buy).
Compatibility is not really an issue anymore. Macs and PCs use the same cables/adapters for things such as printers, mice, etc. (Specifically USB and Firewire) Both have standard network/modem jacks and both use standard wireless protocols (802.11b/802.11g) so you can use your Mac or PC at your favorite coffee shop, friends house, etc and surf away. The only thing that is different is that you use different software. You would get MS Word for the pc or the mac depending on which way you go. Either way, if you write a document in Word, the other computer will have no problem viewing it.