Dells are OK machines. I had a dell inspiron that handled itself quite well. On one occasion it did get the equivalent of a macheads dreaded kernel panic, or the famous blue screen of death. This was no worry, and never happened again. But don't let people fool you about prices and such. true dell offers laptops that are cheaper than macbooks, but these are the basic systems, and lack ALL of the great features on the macbook. apple basically integrated a schooling utensil and a home entertainment center in one, coming with that great apple remote. even the premium dell laptop systems lack the macbooks features, and the models that come close to apples price still have the intel integrated graphics card. only the models that exceed the base MB's pricetag have dedicated graphics cards (i have the catalogue) and still have only 1.6-1.8 intel core colo or duo processor chips. apple has far better service than dell as well. dell has no readily available store of its own that you can bring your computer in to have checked up. and the only way to get hardware in a dell that outguns your macbook is to pay more than what you would for apples new ibook replacement, and many even exceed the macbook pro's price.
as for windows. windows is far less stable than apple's mac os x. plus if like to browse the web, you better have the latest in virus protection software, because the built-in windows firewall is a joke. I've been using PC's for the larger part of my life, and after getting tired of having plastic paperweight towers on my desk i decided to buy my first mac, being the macbook. Dells are toys, and the dells we have in my office at work are no better. they stall, they need constant defraging to keep pace, they need too much attention to things id rather not deal with. my mac NEVER has this issue. macs are actually more practical, despite whatever claims you hear about compatibility with software, and if THAT is your major concern, boot camp is free, and you can borrow a windows disc from anyone that has a windows machine, since the bundled software works just the same. voila! with the new MB you can have essentially two computers in one, if ever you need to do something that requires the help of windows.
i say macbook, its more practical, and lots more fun i guarantee