I have a GeForce 6200 OC with Dual monitor support, current cost, about $60.00 (keep in mind it's only video, not sound and video). I use my TV as the second monitor....great for watching vids or playing games. This particular card allows you to do multiple displays: Clone, which makes monitors 1 and 2 identical. Vertical or horizontal span, which stretches the desktop across two monitors either vertically or horizontally. Dualview, which is essentially two different desktops on one PC. My experience has been that clone is the best option, especially if your monitors are going to be in separate rooms (imagine having to use monitor 2 to change some settings and it's 20' away in another room (Dualview or Monitor1 dies)). If you set Monitor 2 to fullscreen, then you can watch your slide show in a minimized window on monitor 1, allowing you to continue working with the computer, while the slide show would be displayed "fullscreen" on monitor 2, which in my case, is a 27" RCA. My configuration (PC and monitor2 in same room) 2 is set up so that I can use my 5.1 surround sound computer speakers for sound, however I have it hooked up at my Dad's (PC and monitor2 in different rooms)where the sound comes out of his TV so that he can use his remote control to regulate the sound volume. I achieved this simply by buying a line splitter....the sound is coming out of the computer and the TV simultaneously, but the PC is in another room.
The distance your second monitor is from the computer itself is limited only by the length of cable you want stretched out across the floor, and obviously, your ability to multitask while displaying video will be directly dependent on the power of your PC. I have a 2.6ghz with 1gig of RAM.....no problems here, but my Dad has a 2.8 with only 1/2 a gig of RAM......runs kinda sluggishly under the same conditions.
Now did someone say Slideshow?
Shivers Slideshow
Here's an example of something my brother did with some old b&w's from my mother's side of the family. The first pic is my Grandma's high school graduation, the second is my mother's, and around 4 minutes and 17 seconds you can see a pic of my Great, Great, Grandmother
BTW, 99% of these pictures are taken in Natchitoches and most of those at the same house my Grandmother still lives in today.