The short answer is yes I would. I too own a business and it is not doing so well. I would have a hard time going back to work for someone else. I also believe that things will not be getting worse...unless some rogue country drops a nuke somewhere or some other unforseen disaster. Anyway, I think that by the mid to late 2010 things will be better and last for a couple of years.
There are however a number of considerations I would place on any new business. First it must generate cash flow rather quickly as financing is going to be a problem for a few more years. Second, it must be not only viable in slow economic times but it should be able to withstand some serious inflation. I would also diversify my income streams with long term and short term options. Finally I would not have many if any employees. The climate for employers is going to be tough for a few years and there will be a lot of changes and instability. I would minimize my exposure until things settle.
I guess I would add one more thing, be sure to find a way to market your product/services on the internet. Not exclusively but I'm quite bullish on the long term future of the internet and you have to be there and actively market if you want to do business in the future.
For example, I am in the executive search business and I do engineering consulting. The executive search is my main business and I market that with a web site that provides information to consumers of that service. I funnel leads to my business for the folks who can't or otherwise choose not to recruit for themselves. Here's an example of some case studies that show what I'm talking about. Good luck.