With all the flaming going on bashing PCs, I just wanted to chime in with my experience, and give PCs some credit. I do get asked by customers (schools, small businesses, etc.) if brand X has a mac client. For the manufacturers I have worked for, the answer is no. Most customers are used to this. I offer virtual PC options and mobile clients. Most times, this is not a deal breaker. They are used to is. Most software packages (not just security) has this.
I use PCs. I have always used PCs. Everywhere I go - offices, universities, etc., that is what I see everywhere - offices full of PCs, not macs. Yes, there are a few macs here and there, but PCs have been the workhorse of the business world for a few decades. Lets give them some credit.
In the corporate world, with AD, LDAP, full productivity suites, corporate mandated software, etc., there is no comparison. A Mac is limited. Yes, it gets the latest video editing software, but now let's talk about the bulk of the machines that make up large companies...
No OS is perfect. Yes, we had to play around with Windows 98 drivers and XP driver and Vista drivers when it first came out. Yes ME sucked. However, I can take a 10 year old scanner and plug it in to a PC and get it working pretty quickly. Most Macs have a very short life span becasue the user always wants the newest one. Back in the day, the only way to get hardware - scanners, printers, etc. was from Apple for a nice price tag.
It ubiquity of USB devices, etc is from the PC world. Mac tried using firewire, SCSI, etc., to keep their proprietary. They keep holding to their own "standards" to look special. They are the only phone that refuses to adopt micro-USB - until the EU stepped in forcing their hand. All other manufacturers adopted since the 2009 Mobile World Congress.
FWIW, I took a 10 year old PC, and installed Windows 7 last week. The install was so quick - I was amazed. The performance for an old PC was amazing.