If you're not a designer yourself, but don't want your sites to look unprofessional,
it might be a good idea to use a minisite designer.
I have been looking around a bit, and here is the list of the ones I like:

http://www.pixelofgenius.com/
http://www.designgururyan.com/
http://www.minisitefrog.com/
http://blingcovers.com/
http://www.graphicsalien.com
http://www.graphicmavericks.com

These are also ok:
...