%20 in URLs? Is it a problem for SEO?

[emodo]

Simple question:

SEO-wise, is it a problem to have %20 for spaces in urls?

For example, if I have an article called "Jason likes Bacon", it returns Jason%20likes%20Bacon.html.

Of course perferably I would like: Jason-likes-Bacon.html, but that is impossible for a little while.

Thanks in advanced!

[kiwibrit]

From what I have read elsewhere - yes it is a problem.