How to search my husband's computer to see if he is cheating?

First off, what has caused you to believe he's cheating? Phone calls, more "overtime" at a job? Ask him casually who was on the phone, or after one of his extended absences from you, ask him how his co-worker/buddy is doing. Check phone bills, credit card statements, mileage on his car for discrepancies. If you're that desperate to know, you can hire a private detective agency (they can be expensive). You can confront him, but more than likely he will retort with denial, anger and possibly accustations, "you're crazy," "maybe you're cheating,". So be prepared for that and make your decision about the future of the relationship beforehand.