You have to go the whole registration route. It does not end there, you need to appoint an accountant and submit books to SARS every year. If your turnover exceeds R1,5m, then you must register for VAT. A big waste of money IMHO
Is your business name fairly unique, or is it John Smith Computers? If it is a common name then you might find out whether it has been registered. Many people place too much emphasis on the name of the business. I ran 2 sole proprietors for 33 years and both had unique names and one is still going. Another person who might think of a name similar to yours might look in the telephone directory or Google the name to see if it exists
Providing excellent service to the customer, returning phone calls and being honest are the ways to make a business succeed. Word of mouth is the best advertiser and if you can achieve that, you are on the way to success