There will come a time when you get sick of having to worry about choosing between DDR2 or DDR3, different memory speeds and clock timings, CPU sockets, Graphic Cards, driver versions, registry tweaks and stuff like that. I know I was.
I built my own PC's for at least 12 years before I lost interest in harware configuration. I first switched to using different prebuilt PC brands like Dell and IBM (for work) to at least get a computer that was reasonably quiet. Yes I did try out watercooling, but while being more quiet, it was not exactly maintenance free.
The I switched to a MacPro and OS X as my primary workstation at work. Mostly because Visual Studio link times were horrible and also because I found out that OS X is a great developer platform with it's UNIX internals. I will never go back. I happily leave the hardware tuning to Apple so that I can spend my time developing instead.
BTW, my work desktop has 8 cores and can have at least 32 GB of RAM. It's very fast, and what Apple does well is that they don't cheap out when it comes to IO performance, which is what matters most when developing. It was probably really expensive, but it doesn't matter that much when it's company paid.
At home i use a 27" iMac with a quad core i7. Again, quite expensive, but worth every penny specifically because I don't have to worry about hardware configuration.
And just to point out - I don't consider myself a fanboy. I don't care at all about Steve Jobs, or Apple as a company. I just found out that they made great performing, quiet and nice looking computers with a very nice OS that lets me focus on what I do for a living.