Write custom code or adapt an application?

I'm working on a venture that combines straight forward forum functionality with Facebook like real time community discussions. The Facebook-a-like part uses news items to drive entries and encourages the community to comment on them.

So here is the question - would you advise:

a custom coded solution / adapting an open source application (if so can you name one) / going with a proprietary solution (if so can you name it).

For those who respond - I'd be grateful if you could you provide some basis for the opinions expressed.

Rule 1 of a start-up: Don't outsource your core business. If you outsource the core of your business, then why would the person building it need you? If you try to get an investor, and all you've done is repackage existing technology, you may find yourself pushed out of your own business.

If you can't build this yourself, then either hire someone who can, or bring on a partner who can.

Interesting article on the subject: http://www.sdnn.com/sandiego/2009-12-09/blog/giving-em-the-business/high-tech-the-good-and-bad-of-open-source-business-models&urlhash=6VWD&trk=news_discuss (by Phil Morettini in Ultra Light Startups)

The author makes the point that applications built over OS infrastructure (Linux, MySQL) do not have to reveal the source code. If we don't modify Linux then I wouldnøt expect to have to reveal my app code (am I being naive?).

We need a combination of a basic forum - for which OS solutions do exist and, as Jeff pointed out, where the value is in the community not the application.

We also need a Facebook type solution - which we will need to modify - and that might be an element where we need to use OS only after carefully reviewing the particular copy right model employed.

Thanks for everyone's input thus far.

Puk

Question. Is the application the business or is the community the business? That makes a big difference, if the business is the community, then OSS with some adaptations isn't a big deal, since that's not your focus and you should waste as little time as possible on coding.

If you adapt an open source application you need to make that open source itself... I would stay away from that option for that reason alone. No need to have that battle with investors if you are at a point where you can decide not to do that. Once your venture takes off you do not want to have a possible high-visibility battle with an OSS organization on whether or not you should open source your platform because you based it on an open source project. This is a corner you should not cut in your project.

In general I would go on a custom coded solution because it's your core business. You need to be able to customize as necessary. You do not want to cut corners on this aspect of your venture.