How To Set Up Live Input From Cameras Other Rooms

I have a 4-CH Standalone DVR with 4 Cameras, Computer Monitor in main living room. I later set up set 2 more cameras with a new LCD TV for a monitor in the bedroom (have to toggle the two cables because I do not have a DVR in the bedroom).

What I wantto do is view ALL of the cameras from the den/computer room. I have a computer system which can power two separate monitors (have a second matching 22" widescreen monitor I could use). Can I do this wireless somehow? I have dial up internet. If this CANNOT be done, could someone let me know please. If it can, I'd love some guidance as to where to begin. Thanks for any input.