hi chawn,

pretty good point, but what exact kind of business are you looking for to do?

I mean, if you were to repair a computer, using cleaners or defragmenters may become quite boring, since everyone can do it on their own.

if you want to repair things, you might have to focus more on other things, and i didnt understand why would someone even pay you for just speeding up computer, or scanning for viruses, or defrag or whatever.

well I dont think that blind people would be succesfull at the computer repairing business, however you can do  a computer training business at a local blind school where at least you can teach small blind students how to operate the computer, or how to do things, etc.
that one sounds pretty good in compaired to repairing business, you know.

guys like aprone might know more about things like  getting you into jail or stuff , though.

Hey,
  Now a day more then 90% people use computer , and thats why i think computer repairing business can give more benefits.its nice thinking to start such a business.
Casio G-Shock Review

I can't speak for legal issues but here's what I can answer.

As mentioned portable software is your friend. NVDA, CCleaner, and Defraggler all have portable versions. You can stick them in an autorun CD or a flash drive. A USB headset may or may not be helpful for times when sound isn't available, or a set of portable headphones if the user has sound but no speakers.

I haven't used them personally but I believe it is possible to make a disc for an unattended install of Windows. This can be a little specific to each machine due to drivers and those key codes for the installer. A google search should help here, I know I found a lot of information but had no pressing need to make such a disc presently.

The internals aren't too bad for the most part but here are some of the bigger issues. While you can tell most cables apart and most are polarised, meaning they only fit one way around, you won't be able to read the labels on the motherboard which indicate whether the cable is connected to the first, second or whatever such connector. As an example old PATA hard drives need to be in IDE 1 and not 2. Any motherboard which requires the use of jumpers or dip switches could pose a problem but these only need to be changed if you need to make a big system change like a new processor, most new motherboards should auto sense a processor though. If you ever need to replace a motherboard or make a new computer from scratch you won't be able to connect the wires from the chassis, that is the case, for the power/reset switches and the LEDs on the front.

Installing a motherboard in an empty case is doable if awkward, watch your hands because a lot of cases have sharp areas which can give you a cut. Nothing fatal but by hell it hurts and it may cause very slight bleeding. Installing a processor is doable though the cooling unit can be awkward with all the thermal goop. Memory is easy as hell, cards including graphics networking or sound are easy as hell, drives both optical and hard are physically perfectly possible but remember a hard drive replacement may require the transfer of data if the old one isn't broken.

If you're concerned about screwing up the data you can always try taking an image of the hard drive first however. Similar software should allow you to transfer data from an old but functional hard drive to a new one, you'll probably want an external hard drive enclosure or two though so you can connect a hard drive to your computer by USB. Remember a lot of older machines are likely to still use parallel ATA not SATA.