Here is a primer for the uninitiated:
In order to get ADSL in your home you need three things. These are:
1. An active, working phone line from Telkom
2. An ADSL subscription from Telkom OR another provider (see below)
3. A data subscription (to allow you to use the ADSL line for data transfer)
EXPANDED:
1. The phone line can be (currently, along with an ADSL line and preset data) ordered from Telkom for free as a part of their 3 months deal. If you already have a phone line, then you only need to purchase items 1 and 2 (as above). If you don't want to take part in the deal then you can simply ask them to activate your current line (if it isn't active already).
2. The ADSL line is an extension to your phone line. The installation can even be done by the user in most places - it is very easy. This can be bought in three flavours, of which I have listed the cheapest and Telkom prices below.
384kb - practically useless these days for anything except granny web browsing and emails. R152 from Telkom, R134 from
http://www.edgarsclub.net/ (cheapest), R129 from rsaweb.co.za if bought with a data package.
1024kb - probably the most economical option. Suitable for youtube, gaming and downloads (within reason). R289 from Telkom, R211 from rsaweb.co.za if bought with a data package (cheapest)
4096kb - High speed, suited for HD youtube, torrents, downloads etc. You can go crazy with this one. 413 from Telkom, R370 from edgarsclub.net, R322 from rsaweb.co.za if bought with a data package (cheapest).
3. The data options can vary massively. Telkom will try sell you high priced nonsense that is worth a third of the cost, so don't bother with them.
Data comes in three forms - you can get uncapped, capped and prepaid. Uncapped is great if you use a lot, but more often than not the speeds are slower in the day - this is called shaping. You run the risk of being throttled (slowed down for the entire month) or even having your account suspended if you go crazy. Uncapped is generally OK for local gaming but international servers might be a bit laggier than capped. Capped is generally faster but much more expensive. Prepaid usually has an expiry date and can be used like phone credit - it doesn't run month to month but is exceptionally costly.
For uncapped I would recommend mweb.co.za or openweb.co.za - these cost about R299 for uncapped. (EDIT: there is currently a 1024kb uncapped for R229 deal going on with Openweb).
For capped, a very little known but reliable provider is BTWeb.co.za . These guys sell data very cheap (30GB for R300). If you foresee yourself using more than that, then go for uncapped. The data they sell is fast and never throttled. I have used them in the past and was quite happy.
Don't even bother with prepaid.
So, in conclusion - make sure the phone line is working, get an ADSL line from Telkom (either on the 3 month deal or not) then buy some data. To install the use of the data you change the name and password on your router, hit restart and let the fun begin!