there is no true HD webcam streaming yet.. you have one of the best video quality, but this doesn't mean its HD . No offence. HD starts from 740p (1,280×720) or at least 480p
http://en.wikipedia.org/wiki/480p, which is not HD, but HQ.
You sort models by resolution and frame rate, which is not fair for many good models.
For vittle, i wish you success with your future studio

, you should take in consideration the sponsor from my signature.
Put your girls on 4-5 sites (no more than 5). For webcam splitting use Webcam Splitter (you don't need the pro version)
http://very-soft.com/ its like 20$. There are some free alternatives, but this is the best one i have used. AWE (livejasmin.com, the sponsor from my signature) used to give free licenses of vCam
http://www.e2esoft.cn/vcam/ , a pretty good webcam splitter but with lots of bugs, not recommended.
Quality its important! Buy at least quad core PC's. You will need them if you are going to stream on maximum quality on 4 or 5 sites. Encoding takes a lot of your CPU power.
For 5 stations you will need at least 15 mbps upload bandwidth.
Use DeepFreeze (it cost you some money but will save you a lot of nerves), this software will remember and restore all your default settings you make on a webcam station.
Like JustDaveXxx say, don't let girls on facebook, hi5, myspace, yahoo messenger, msn etc. Block these sites from router.
Make clear rules for the girls. I don't pay them daily, i don't think its a good ideea (tested) but its very very important to pay them on time (when you say you'll pay, pay!). I pay them on 2 weeks.
And yes, dealing with cam girls its a real pain in the ass, but you can make pretty good money and sometimes its fun. Don't hire any bitch! Few good girls like 10 can make you money like 50! Go with quality not quantity.
In my city are like 40 studios, i still survive
