I have 3 bookcases still in flatpack, and 30 to 40 banana boxes (mostly computing stuff, but books in there too) in the two sheds, which have not been touched since I moved in, January 2012.
I still have about half of the computers (my sister and I took around a dozen to the council tip in October/November 2011). It really felt like half my life was being trashed at the time, but essential to empty the house for auction, and now I'm in 2 up, 2 down (well, 2 up + tiny bathroom, and 1 of the down is the kitchen) it was good she was so tough. I still have at least half a dozen laptops, 5 iMacs, 42", 40" and 32" (+4x 22") TVs though (the latter group used with some tiny, almost silent, 'nettop' computers... so small can be fitted to back of a TV and are almost invisible).
If you can rid yourself of a portion, eg to a charity shop, then great (but I'd make sure it was one you don't go past, so you are not tempted to check which items have sold, nor what prices they have been marked at).
The books I have (tiny number of sci-fi) are nearly all computing, mostly bought on holiday trips to USA, and I had to buy an extra suitcase to bring them back. Many came with CDs and were reduced from $50-$75 to $10-$15 but that was 10 years ago, and most have only briefly been used. I also bought two 'corner' cases from British Heart Foundation when I went on a 400 quid spending spree, the day they opened in March 2012, and have not yet dragged them upstairs, but this week I hope to swap bedroom to front and 'office' to back (as sunny days are too bright and I cannot see the screens well enough, even with the blind closed)