Someone on twitter started a #goonline tweet where people are describing when the first went online. I twittered stuff until I realized that I really needed a blog post.
I have been teaching CS for 16 years, so you can probably imagine I've been involved in computer for some time.
Since I am a ham radio operator, etc. Most of my computers have been home built.
My first real computer though was a TI-84 computer (real meaning it plugged into the wall, had a monitor, could save data, etc). Primarily because I was working for TI at the time. My second was a TI PC, company issued. That was when I really first went online but only to the company computers. There wasn't really any where else to go.
My first real online experience was Prodigy as it had a fixed price. I couldn't afford AOL. Once Prodigy realized they were bleeding money, I left to be online with FIDONet and became a node on FIDONet. I was pretty active with that group.
I had the second private internet account in the Dallas Fort Worth area with Texas Metronet. They were the first here that allowed private accounts, not associated with a university or with a business.
Most of my computers have been home built until recent years. Now I buy refurbished computers at Fryes, usually under $300. My philosophy now is that cheap and more than one is better.