Macbook vs Dell laptops  

I have the same problem as you. but i think both are good and can satisfy your request.I use HP laptop and XP .I heard of Macbook,I think it is also good but less popupar than XP laptop!

Well it all depends what you are using it for. I wouldn't suggest a MacBook for a gaming platform, but for pretty much anything else you'll find Mac far superior, although there is a learning curve switching from Windows to MacOS. The MacBook will almost certainly have a longer usable life. I am a computer technician by trade and have worked with both Mac's and PC's.

it depends which use you are going to do if its programming or easy jobs its better to buy a dell but if you are going to use to edit graphics ore edit videos it better a macbook

This depends on how much money you are going to spend and if also which one you think looks better. They are both very good notebooks, but they differ in some categories for which I would give my personal opinion.
The Macbook is definately the better looking one from my perspective, since it's thinner and has a uniform thickness. But the dell xps has that kind of varying thickness common to almost all PC notebooks. That's one of the things I prefer. If you're going to rest the notebook on your lap (as a laptop), or uneven surfaces, like on a bed, pillow or couch, the macbook is better because unlike most PC laptops, the macbook pulls air through the top (by the keyboard) and pushes it out the back (on the rear) below the screen hinge, where as the xps does pull air from underneat. The macbook pro (13inch and bigger) has a backlit keyboard so you could continue to type in the dark. I believe this option only comes in the xps 15 inch+.
You can install Windows on a macbook with the use of the bootcamp software. But you typically cannot install mac os x on a PC laptop without special hacked software.
The macbook will give you generally less performance for your money because it is a more expensive just like all apple products, but it looks good. But this could change tomorrow. It's best to just take a look at the side and see all the possibile configurations you can get. You could order a macbook or a macbook pro, and any of the xps laptops.

I have no idea which laptop is better. I had a couple of laptops or notebooks, the difference is lost on me and I don't particularly like it because it is not as fast as my desktop nor as easy to use. I hate small keypads. cheers!!