it really does depend on how you would like to approach the project, im sure there are a few prebuilt engines out there which could help you get started. although if your programming experience is good then i would say definitly consider creating your own, over the last 4 weeks ive had a text based RPG to create as an assignment for university, it hasnt taken me long and ive almost built a flexible rpg engine from which stories and game logic can be constructed just by editing text files, although currently is only single player, might take a few months to combine network support into this.

as youve said come from a internet technology based background it might be an idea for you to construct a web page based rpg, you would be able to write the entire thing in any web based language and host on your server setup

legend of the green dragon is a php game like this, and it's open source. You can look at it, and modify it to your heart's content. lotgd.net