Hi Cav,
This is unsolicited advice, but in the long-term neither the living together or the attempt to hide searches for Pr0n, old girlfriends, meth cooking instructions, local singles sites, etc. will work out. They all slowly destroy trust, break-down intimacy, and kill relationships and all of them inevitably spoil a marriage.
But if you are determined to try, judging from anecdotal counseling evidence, the best method for hiding your internet activities is third party software like System Mechanic which comprehensively erases your tracks and shreds the recycle bin. However, If she's at all PC savvy, she'll figure out something's wrong, these days a spotless computer is usually a bad sign...
- SEAGOON