If you're the first technical person in a company, you're either a founder/co-founder or an chump. I simply not only refuse to answer emails from "business guys" who "came up with the next great idea and are looking for an engineer to build it", but I also will not even consider
funded start-ups that don't have technical co-founders: it's safe to say, that they will lack true technical leadership and their engineer team will be composed not of people who wish to work in a start-up, but of people who have nowhere else to go.
More often than not, if you look at successful technology companies even the "business guys" (the CTO and even the CFO) often have an EE/CS/Math/Physics degrees and have, at one point, have held technical roles. Engineering/math/natural sciences act as "brain gymnastics" which come in handy in any role which requires fast, analytical thinking.
That being said, in enterprise software having a strong sales team is often more important than having a strong product. Ideally, you'd want to have a founder who had worked in roles such as field sales/application engineer/sales engineer/consultant and has a Computer Science background: this way they will understand both the technology involved and the acute pain the target customers experience.
For consumer Internet, however, "sales guys" are only needed when you have something to sell (e.g. a critical amount of impressions in an advertising-supported site). The canonical examples (Craigslist, eBay, Google AdWords/Overture) are brilliant in that they're self serve: you don't need a large sales force to sell them.