As someone who used Mac computer's my whole life, I can tell you I prefer PC's. People may say Macs are great for X or Y, but in the end they are still just computer's. Almost every Mac I had would experience the same thing, ~2 years in it would start to slow down, and the speed would never be what it once was. On my current Windows 7 Laptop, I have almost the same speed i had on day 1, almost 4 years ago. In my opinion, Apple Computers have almost nothing to offer. I love CAD on windows, Image and Video manipulation on Windows is no harder than on a Mac in my opinion. The real deal breaker in my opinion though is how helpless you can be as a Mac owner, many times if something goes wrong, and yes things go wrong, the only recourse is to take it to an Apple Store. It is possible to buy the tools to open up a Mac, but I wouldn't know where to begin on that. There is so much information out there for trouble shooting a PC, and I never bet on a zero-problem computer.
As for my computer history... I had pre- iMac macs, as in big beige squares, then i had an iMac, then i did a Mac Pro, then the new iMac that is just one big screen.
The first PC i had was an Dell with XP, i got it to play games that weren't compatible with Mac. It wasn't very special, however when I decided to switch full PC I bought a Toshiba Qosmio Gaming Laptop. It was 1500$ on Newegg, and it has been by far the best computing experience of my life, At the time I bought the laptop, Mac didn't even have a comparable platform, and their most powerful laptop would have cost 1000$ more at least. Almost 4 years later and my laptop is still chugging along.
Does it matter whether you buy a Mac or PC? No, but when you are on a budget, I put my money on PCs.