Smokyo

Most tourists and foreigners head for the big stores around the station. The locals look past these and head for the cheaper more specialized stores in the back street. Many of these shops have crates outside with lots of cheap computer parts and accessories. This is a map of the area. Most of the cheap new and second-hand shops are located in the top left part of the map.

http://static.photo.net/attachments/bboard/00G/00GpE5-30400784.gif

I always do my computer shopping in Sofmap. They have loads of stores around the Akiba area. They all deal with different lines of products. PDAs, Computer Parts, Mini Note books etc but you can find info about the various outlets at any of the shops. They are mainly secon-hand shops but they give you a couple of weeks warranty on your used computers. Bought me a nice IBM Think pad there 3 years ago and its still working OK.

These are the three biggest electronics stores in Japan. 

Bic Camera. http://www.biccamera.com/

Bic Camera have a huge store in Yurakuch in Tokyo- it's the flagship store and the one where Michael Jackson spends most of his time when he's in Tokyo.

Sakuraya http://www.sakuraya.co.jp/

Yodobashi Camera http://www.yodobashi.com/enjoy/more/index/index.html

Yodobashi's biggest is in Akihabara (Akiba) and is the biggest electronics store in Japan (the world???)

Websites are in Japanese but it may give you some clue as to prices and products...