What (pixel) dimensions to store jpg? And use in slideshows.

I am trying to do some filing to reduce the amount of disk-space I am using for my images. In most cases I keep a RAW or full size .jpg, but for general browsing I am trying to keep reduced images in separate folders. This makes it much quicker and easier to browse lots of images or show people stuff. Initially I chose 1600px as max. dimension, but now I am thinking I should use 1920 (as HD is 1920 x 1080) My main monitor is 1820 x 1200. or should I use 1080 as min. dimension as most display programs (e.g. picasa or windows xp slideshows) seem to fit image into the screen area leaving black areas.

Of course I want to be "future proof" and have good size for iPad, TV(?) etc. Slideshows can also be "pan and zoom" (and more I imagine) how would this affect the best size to use?

I want the best choice for best full screen display with minimum dimensions. What would you use?

Buy more hard drives. Keep raw files

Digital projectors all have a 'native' resolution, even though they might support many other pixel counts for a frame size. Their best performance will almost always be at their native resolution. In particular, color fidelity is often more compromised when they are not operating at native resolution.

For the above reasons, my own approach woulbe be that I would create a folder of projection resolution files, while keeping other versions of the file at the full native camera resolution in another folder.

To clarify I keep Raw or larger jpgs as "originals" but for general use I use "developed" (reduced jpg) in separate folders for browsing or showing on PC screen etc. I also upload some stuff to Google picasa online, normally at 1600px max.