Oh so many ideas, I try to keep it at least 18" away from florescent lites. Runs parallel to power I try to stay in the next stud bay over, about 16" or so. More important than the actual distance (IMHO) is the limited amount of exposure of the CAT5 to possible noise sources. You can squeak closer for short distances if you need to. Hope that helps, if you want more specifics I would refer to the EIA/TIA standards.
Good Luck It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com