hi compitaveggie, first off, welcome to the forums!
In answer to your question, the best cameras to use would be ones designed for CCTV, that being ones designed to be on 24/7 and provide the best price
erformance ratio. You mentioned using your PC, there are two main ways to hook up security cameras, first is using an external device called a DVR (Digital Video Recorder). Typically something like this:
http://www.maplin.co.uk/Module.aspx?ModuleNo=36351&criteria=DVR&doy=27m8
It's a 4-channel DVR, records straight to a hard disk internally, this way doesnt use your PC though, and im guessing you would want that, most probably for easy playback and editing/managing of clips.
The only decent way of getting security cameras to display, record and be managed on your PC is to have one of these:
http://www.maplin.co.uk/Module.aspx?ModuleNo=98551&criteria=bnc pci&doy=27m8
Standard PCI card with 4 BNC sockets on it, BNC being the type of connection that nearly all of todays security cameras have. It's become sort of universal. With that card in place (and the provided software installed on your PC) all you need is (up to) 4 cameras to connect.
Cameras:
This first one is your standard black and white security camera made by Swann (good security brand), high quality images, fully weatherproof if you ever wanted to use it outside amd these models ave infra-red LED's in them so they can see in total darkness, excellent for nightvision:
http://www.maplin.co.uk/Module.aspx?ModuleNo=98273&criteria=swann&doy=27m8
The next one is the same camera but its a colour version, looking about £20 extra for that, but it depends if you really need colour images or not, thats up to you to decide, both cameras are very good basic models:
http://www.maplin.co.uk/Module.aspx?ModuleNo=98269&criteria=swann&doy=27m8
If you wanted to step it up a notch and get even better quality images and a bit better range on the nightvision (other models are limited to about 20-30feet night range) then these following cameras would be more suited, note the sudden jump in price though:
http://www.maplin.co.uk/Module.aspx?ModuleNo=220738&criteria=swann&doy=27m8
http://www.maplin.co.uk/Module.aspx?ModuleNo=46565&criteria=swann&doy=27m8
http://www.maplin.co.uk/Module.aspx?ModuleNo=98302&criteria=swann&doy=27m8
The first one has a range of just over 60 foot nightvision whereas the 2nd and 3rd cameras can see in pitch black up to 150 foot. All of them are 100% weather proof for outdoor use and they can all be used perfectly with that BNC PCI card that i linked you to earlier in this post.
All in all, for a decent-ish set up with say... 2 colour cameras you'd be looking to spend about £200-£250 GBP
I understand you might not be in the UK, if this is the case then this post can be for info rather than prices, hope it helps
dragon2309