How many channels do you plan to offer?
You need something that will encode the content in the proper format for wowza - do you have any plans for that? This can be some commercial encoder, but you need to take care of it’s capacity (number of channels, bandwidth). This encoder can also be a PC with appropriate cards, but the capacity is still something to take care of.
If the solution you choose cannot send the proper format to Wowza - http://www.wowza.com/products/streaming-engine/specifications - you’ll need to do transcoding, which can be done on Wowza (simplest) or on external transcoders. Bear in mind that transcoding usually requires a lot of resources.
What do you mean by “capture PC”? Something for recording content or the server to catch satellite streams and send them to wowza?
If you want to offer some additional services (such as applications on STBs, time-shift, DVR, VOD, etc.), you may need a middleware, storage, DRM. You’ll probably need some networking equipment as well (a switch at least).
If it’s not a closed system, or if you plan to offer different packets to customers, you’ll need some sort of security mechanisms in place.