Depends on your requirements really --

If you want to browse the web, use applications like MS Office, and do email and things like that, then a laptop is good for portability. If you get a wireless router as well, it gives you the ability to use the internet remotely from anywhere on your property (including the back yard). Also, if you get a laptop, you can also get a docking station (like at the desk you would usually sit at) to have a full size monitor, keyboard and mouse (since using the laptop keyboard and touch pads are often a pain in the backside).

If you were looking to play high end games, do high end graphics or video/audio manipulation, then a good desktop may give you the higher end hardware that you need for those applications. (Note - a laptop will still let you play games, and do graphics and video/audio). If you plan to stay in one place and not move around, or don't want to take a laptop with you if you're travelling, the a desktop may give you a chance to get some higher end hardware.

For example, i have a laptop with a docking station to a Montor, mouse and keyboard. I do all my photo editing, word processing, internet use, downloading, uploading, as well as some pretty memory intensive programs for technical writing (amongst other things!). A laptop is really fine for most peoples' usage these days, and gives you the ability to move around and use a computer from anywhere.


edit: you would think i could actually spell the word 'Like' correctly