It matters a lot. It is the primary meme that you want to get stuck in people's head. It must be meaningfully associated with your brand, and have all the right connotations.

Check out RWW's list of best/worst logos for 2010

http://www.readwriteweb.com/star...

based on this longer list:

http://blog.designcrowd.com/arti...

A great logo is well worth spending a good deal of time on. You need to spend a lot of time thinking about positioning (what's the market, who will use the product/service, what perceptions do you want them to have, whether they will expect a youthful, fun logo or a more serious logo, etc.) You then give your graphic designer a broad creative brief that gives them room to produce something that matches your positioning. You then iterate till it is something you really fall in love with.

Keep it as abstract and zen-like as possible, because people's primal memories work better with simple, visceral symbols. That also gives you positioning flexibility later.

It is not nearly as important as your wordmark, and you can actually do without a logo altogether, but I don't recommend it. Visual memory/association is much more basic than verbal.

It is important that you fall in love with the logo if possible. Just as the name should be something that makes you care about what you are doing at an emotional level. There's an objective, market-driven bit to these key marketing decisions, but if you don't let your subjective tastes influence the decision, the logo/wordmark may become objects of hate for you and your core team, and a source of aversion.

Sure you can start with a hack. But at some point, if you are serious, pay a good designer. Well worth it.