My wife had a toshiba before she got her MacBook. After four years, the batter was dead (actually dead after a year or so), the case was cracked and broken, the DVD drive fell out, and the screen would no longer close. When windows crashed we couldn't even reinstall from the restore DVD, as it wouldn't use an external DVD drive.
2 years in her MacBook is still in one piece.
Sure you can find a cheaper laptop, but start with the sticker price you find on the dell website for their entry level laptop, and put decent ram in it, spec up the processor, add a full copy of windows, webcam, firewire etc. Then add what garageband and co are worth to you (easily $100). THEN compare that to a MacBook. Works out about the same, and you still haven't got a MacBook.
Ian