i am not sure what you want to put in the drawers. they should be as wide as they need to be to support whatever you will be putting inside them.
if you build the base section first and dont put the top on yet you could work out all the drawer slides rather easily by installing them as you work across putting the drawer verticals in. i would say to go with a wooden slide for ease of construction however yo ucould go with cabinet slides if you dont mind extra work aligning them.
five drawers would be 1.8ft each (550mm) which are wide enough for most common items you would have in such a unit such as games, movies, etc. you could of course get away with as you have it.. smaller drawers if it works for your items. you're going to have to build the bottom first and top last though if you do smaller drawers so that you can work on them. remember... you will lose a bit of width and height on the drawers due to construction as seen below so a bit wider drawer area then what you need would be suggested!
if using .75inch thick (19mm) plywood/boards...
lose on height: thickness of plywood + small gap at the top + small gap at the bottom. estimated 1.5inch loss (38mm)
lose on width: 2x thickness of plywood + 2x thickness of slide. estimated 3inch loss (76mm)
you can see an example of what i'm talking about here although it uses metal slides instead.
http/www.idocabinet.com/pic/Side%20Mount%20Self-Closing%20Full%20Extension%20Drawer%20Slide.jpg you not only lose a bit of space for the gaps around the drawer but also for the thickness of the drawer material so your actual useable space is less than the space you put into your frame.
if you look at the "build" link in my signature you can see what i personally use. its a product called panduit and while i'm not sure if that particular brand is available wherever you are... an equivalent likely is. its an industrial cable management option for control panels.having the snap on cover and wires coming out the sides really is quite handy for keeping things nice looking. agreeably the picture of it right now isnt the neatest that i've ever had it and there are more ways to improve it but it works well.
another option would be to install some desk wire frame cable tray behind the cabinet. this works nice, however if it doesnt have a lid some awnry cables tend to push themselves up and out of the tray!
transformers on power supplies are another issue. they do not fit very well into most trays. what i've been doing is to put a few eyehooks screwed into the underside of the desk and zip tying them in place like i did here http
/postimg.org/image/5n4p3vup5/ its not pretty but i didnt use panduit or cable tray on this desk... and its 100% better then the rats nest it was.
its also possible to do something like this
http/cloudfront-assets.unclutterer.com/wp-content/uploads/120210-wow.jpg but its a bit more work than using tray and requires more zip ties making it a complete pain to undo if you ever want to change things up or clean things out. i would suggest this method for big power transformers and the like but it may not be ideal for cables.
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as for your design above...
- if you plan on going with the 7 drawers i would line the verticals up with the verticals below. this looks nicer and makes it easier to construct. of course if you go with a different number of drawers this will change but tend to keep it symetrical from left to right.
- remove the spacer between wii and wii u. this is not needed.
- you have some strange double-frame lines going on in your drawing for some reason. your cabinet will only be a single thickness as shown in my drawing.
- your drawers will be a bit oversized to the holes.
- if you wanted to make it looks a bit more presentable... you could make a faceplate for the front like
http/www.crwoodworking.com/Face%20Frame%20test%20fit.JPG which would go around the whole outside edge, around the doors and around the drawers. it would also go down on the verticals. basically it would go overtop everything but your adjustable shelves this will cause you to lose a bit of space for your drawers but looks alot nicer. here is an example of frameless vs framed
http/tonyscustomcabinets.com/yahoo_site_admin/assets/images/frameframeless2.26115832.jpg