I have a wireless Roku and though I've never hooked it up to my projector, I'm sure it would look good. I sometimes hook up the Wii, just as it's more conveniently located, but it's more pixellated for me than the Roku.
Roku has a number of channels that will stream content (notably Netflix and Hulu Plus - NOT the same as Hulu online, although similar). If you are computer savvy, you could rig up the Roku to play CBS, for example, through one of the private Roku channels (see this forum - http://forums.roku.com/viewforum.php?f=28&sid=472e986f4c92f26c7dada358abb7cda1
- for more details), but unless you wanted to do that regularly, it would be easier to just hook up your laptop when needed.
I think the new high end Roku 2's have both wired and wireless capability. Wired is more stable, obviously, if you are worried about that, and would be fine for usual TV watching. Saying that, I haven't had any issues with wireless since I upped our internet connection. I think we have At&T DSL Elite, which states a speed of 6 Mbps, and is fine for SD content. Don't have a HD TV and rarely use my 720p projector for streaming, so I can't say what would be needed if you want to go that route.