I'll jump in as Devil's advocate
I have spent just over half of my digital recording life on a PC (originally) and the rest (5 years) on a Mac. I'm now on my 2nd Mac (PowerMac 8 core)
I, like RawD, built my own PC's and generally it worked quite well. Most problems were related to either:
a). upgrades (recording software and operating system/patches)
b). plug-ins (with the 'freebies causing the most issues)
both of the above had to be downloaded. As a rule I did not leave my recording computer connected to the net. I was on ProTools and their upgrades were notoriously 'buggy" and I soon learned to wait some few months before updating. In general "updates" were a bigger headache
When faced with a system requirement change in order to continue with the 'latest and greatest' version on Protools (or some of the commercial plug-ins) I looked at building a new PC... or buying a Mac. Mac's are pricey, no two ways about it. Friends who recorded on Macs never had complaints about issues, seldom if ever had to reload software and crashes were usually operator induced and relatively easily repaired.
and I'm now mainly using Digital Performer and sometimes Reaper, and very once-in-a-while Pro-Tools. Macs do have updates, but as of yet, I've had no issues with any
Regardless of which system you decide upon, you'll need to consider latency. This is both determined by your DAW as well as your interface, and of course computer processing capabilities. I am (of late) utilizing more and more virtual instruments ( orchestral, horns, synth, some keyboards ). As I play with a drummer I've not used virtual drums, but I've managed to run sessions with 16 - 20 instrument tracks, 10 auxiliary and 12 - 16 virtual at low buffer without issues.
I should declare The Mac has 10 GB of memory, 4.5 TB of storage, and I have a UAD-Solo accelerator card. I run my DAW software through an RME FF800 clocked to a Lucid 8824 and utilize all 28 I/O.
My best advice is to really identify your recording needs and then proceed to obtain the best hardware you can afford, even if obtaining this piece or that means you have to wait and save a bit.
Ultimately, while the equipment can impact noise and artifacts in your recordings, it is mainly your efforts and attention to details (aka "listening") that determines the quality of your finished pieces
While much of the recording software and hardware is marketing hyperbole, hype and innuendo, there is a difference between entry level/bargain gear and the more high end
let us know what you decide