My opinion, millage will vary... As with anything else, you get what you pay for. If you purchase a $40 4 port capture card rated at 30fps sure it will capture 4 video streams but it is at no more than 7-8fps per channel and it will chew up your CPU because it is relying on the PC CPU to encode and process the video.
As DotNetDog pointed out, IP based cameras have a ways to go. The fundamental problem is that the IP camera has to do too much to be good at everything. If you think about what it is doing, in such a compact form factor, quality camera that works in both bright and low light situations, video capture, motion detection, transmit the video, web server, etc, it quite a bit to ask of a device. Secondly you are paying for redundancy, that is, you are duplicating that functionality for each camera you install.
I started out with ZoneMinder a cheap 4 port capture card and really cheap cameras on an old dell desktop I had. The result was I had video, with not very high quality results, but hey, it was less than $200 total.
I'm now running the following: (switched from consumer to professional grade)
Intellicam USA These are Sony sensors cameras built in Korea, excellent quality. (I'm running the last generation of this camera) IP66 weather rated, etc, roughly $200. Whatever camera manufacture you go with (there really are only a handful of OEMs for these cameras) the better ones are going to have Sony CCD video sensors in them
HIKVision This card is made in China, has a Texas Instruments DSP chip called DaVinci that does all of the video processing, motion detection, encoding, etc on board. Roughly $800 for 8 port version (full 30fps on each port) with 3rd party professional CCTV software.
The card is plugged in to a desktop pc with a TB hard drive. Currently I have 8 of 16 channels installed with 21 days of recordings taking up roughly 300gb of disk space. CPU runs around 5-10% ($450 HP desktop) a bit higher when clients are connected. So it's not the architectural approach, it is the quality of the capture card.
Whether you run IP or Analog you still have to run cable for power and connectivity (network or video signal). In my case I am using cat5e with video baluns at each end; power is also run over the same cable. Cables are home run to a single 20amp digital power supply and capture card.
At the end of the day it will come down to how much you are willing to invest to achieve a result that you can live with.
-Ben