I brought a PC from them back in March and its great. I got a 19" TFT with it and although I hadn't heard of the make of the monitor it has a very crisp picture and a good response time. The other components are top quality and so far no problems.
I would recommend them highly, even though I was slightly annoyed at the delay in my delivery (3 weeks instead of 2). I looked around for ages at the time and PCS always came out best in terms of price for quality. Don't get me wrong, companies like Alienware will have better quality components but you'll be looking to pay twice as much, which isn't worth it as PCS components are very good anyway.
Check out the testimonials on there website for more info.