That's expensive for a macbook, look at a refurbed MBP, you can get the 2.2c2d with an 8600gt in it for about $1600.
Macbooks are nice for $1000 for the base model. I'm not a big fan of 13" laptops and integrated graphics, but then again, I do a lot of work and gaming on my two laptops and only really use my desktop as a server.
The Dell is going to be a better value hardware wise, but take a look at the refurbed like I mentioned above.
OS X is a good operating system and I like the way some of the programs operate vs. Windows, but then again you have to look at a couple of things, like what programs do you use on your current Windows setup and what are you going to use on the OS X side. If you have a ton of pay for apps and can't find a free substitute on OS X, it may not be worth it. Some companies like Adobe offer OS "switches", where you can switch your currently registered product from one OS to another up the three times (I think that's the magic number, don't quote me).
So if you're going to have to spend $3k on software ontop of your purchase, or you don't know where to get it free ((oops, sorry, I didn't just say that)), then it might not be worth the switch unless you plan on sticking with OS X forever. I know my next computers are probably going to be Apple. I purchased my MBP just to run Logic on it for recording at a studio I opened several months back and through just using it on a regular basis as well, I've come to really enjoy OS X. There's little things I like that you can't do with a base version of Windows.
That being said, I've also been running Vista on my 17" Dell Inspiron (1920x1600 res screen, 2.0 c2d, 2gb ram, 256mb nvidia 7900gts) notebook. It was my primary machine and is my gaming machine. It blows the MBP out of the water when it comes to doing anything involving games. I'm also torn on photo editing as well, since my pictures usually seem to come out better when using the Dell, plus the larger screen size and resolution help immensly.
There's good and bad about every system IMO, it's just a matter of what you feel you want to do. If you're serious about completely switching and don't want to spend a ton of money on a good computer, look at the refurb deals. If you want a Mac to toy around on until you can sincerely make up your mind and decide to spend $2000 on a serious heavy weight machine, then look at an Intel Mac Mini.
With the Mac, you'll be able to either dual boot into OS X or Windows or run OS X with an emulation software for Windows. So, it's not like you'll be stuck if you switch. It's just pointless to buy a Mac and run Windows more than 75% of the time.
Also, I honestly didn't read the rest of the thread, but if you're interested in gaming at all, any of the new Macs with a video card should be able to handle gaming, as long as you're not trying to crank it to max settings on a huge resolution...then again, you'll be running your games through Windows unless you purchase OS X version.
So, if you haven't already, assess what software you currently use, which of it is critical in your choice to using a computer, and then look for alternatives, etc...then look at the other goodies you can find for the Mac you want and then decide.
Also, if you're close to an Apple store, go play around. You won't get anything near the experience of owning one, but it's a start.
