I have been told that analog cameras should not be run more than 100 feet from the P.C. if more picture quality really suffers, I need to go 200 - 300 feet (infrared bullet cameras) to GV PCDVR System.

that should be fine, you do loose some video quality though. If you wanted you can always get a video amplifier also.

Make sure you use at least RG59 cable, if using Cat5 should not be that much of an issue. Any un amplified video no matter whether it is RG59 or UTP/Cat5 cable, looses quality over 100 feet.

Try to make sure that you power it locally as well

If you use good quality RG59 and power the cameras locally, as already advised, then there should be no problem over these distances.