I use a cheap, wired IP camera (D-Link DCS-910) and it has been amazing...no lockups, etc. You just need to take into account several things before you make your decision(s):
1) Wired or wireless? And if wireless, make sure that you read reviews concerning the signal strength/quality. If wired, can you run the cat5 AND can you run the power over the cat5 (more expensive) or is there an electrical outlet very near where you want to add the camera(s)?
2) Do you need audio? IP cameras won't provide audio (iCam limitation)
3) Do you need low-light vision? Again, read reviews and make sure the camera actually has a quality low-light image. Consider IR lamps to improve things...maybe a motion detected IR lamp?
4) Overall image quality? I'm guessing that since icamsource narrows the image size down to 640x480, it has to work harder (slowing down your computer potentially) to change camera images from higher resolutions to 640x480. With that being said, if you use a program called ManyCam, it is probably possible to use the camera's original motion detection software to store the higher-res images and allow icamsource to manipulate/save a 2nd set of lower-res images. Remember that some cameras (such as my D-Link) have a focus adjustment piece that you can rotate. So if you fire up your cam and it's blurry, try rotating the piece around the lens.
5) Where are you physically locating the camera? Remember that areas near windows and obviously any area outdoors are going to generally be exposed to larger temperature variations (think condensation inside camera) and possibly exposure to water from rain, etc. Do you need a weatherproof and/or heated enclosure? Do you need to leave the window blinds up to reduce the temperature variations? Or if you don't want to worry about that, yet still place them in questionable areas, you'll want to plan on replacing the cameras occasionally.
