Most professional video conferencing solutions use dedicated hardware, not a PC. Where I work have just invested in a system from Lifesize, however I can't comment on it because it's not up and running yet. My boss was very impressed with a demo he received.
i would be very grateful for any feedback you can provide about the lifesize solution as one of my customers is also looking...we're a way off yet, since we need to get them a proper managed internet connection before we can proceed...but within the next 3 months i would imagine they will want to bring it on-stream so to speak.
If you are looking only for Video conferencing, there are many exclusive video conferencing vendors such as Polycom, Alcatel, Accutel, Vidyo, Vidtel etc. However, if you are also looking into web / video conferencing combined services, you may have a look at WebEx, gomeetnow, gotomeeting etc. or even consider having on premise web-video conferencing appliance installed such as RHUB appliances.
we have been using lifesize team mp and express units. betweeen the uk, china and usa office it works really well, its dam expensive a replacement camera is 4k!
we do use MPLS for the connection to make it solid.
you can download a client on to a pc and get a laptop in the loop as well.
i would say avoid the expres units as it can only initiate 1 call but can take 10 calls in. but is limited in other ways.
A replacement Lifesize camera should not be costing you 4k! Who is that through?
Also, what limitations do you have with an Express codec? Not sure what you mean by 'take 10 calls in' - the Express does not have any built-in MCU capability so it can join a multi-party call that is hosted elsewhere but cannot host a multi-way call itself.