but generally prefer a Mac. They tend to be more expensive than a PC, but the newer Intel ones are very good. One of my Macs is the entry level MacBook - the white one. I put 4GB of Ram in it and OSX just flies on it.
You've also got the option of installing Parallels and having a Windows OS installed, so if you ever need to you can switch over to Windows without having to reboot. My Mac Pro has OSX, XP, Vista and Ubuntu and can run them all at once in different windows if I want it to - very handy for checking cross platform / browser compatibility with websites.
I guess it all comes down to what you need it for and how much you are prepared to pay. The basic Mac laptop cost me around £700, with another £60 or so for the RAM upgrade. You've then got the option of Parallels but of course this means buying a licence for each operating system you want on there. With PC laptops as cheap as £299 now you need a pretty good reason to spend close to a grand on an entry level Mac.
Having said that, I did, and I won't be buying a PC again.