Only just discovered this thread. I voted for rarely - this is when I check out rogue applications for AV vendors and download through the sandboxed browser, but I haven't done much of that lately. Most of the time I'm not sandboxed.
Sandboxed 99.9% of the time. Reasons: Protection + Don't want any unnecessary clutter files. My browsing habbits are positively lame but I like the little bit extra firewalling strength Sandboxie has - I see Sandboxie as an added layer of application firewalling.
Ran Sandboxie that good for downloaded stuff that you don't trust to open. Then you can see what's inside of the file. As for the Browser I didn't see much protection there even with that program nor with GesWall. Now not using them makes life better. Years ago RamDISK large enough to house the browser cache would be ideal but now with these virtual software base still slightly slower if they crash then you're up the creek!
Both IE8 and FF are forced to sandbox under Sandboxie. As long as you allow bookmarks and, in the case of FF, addons to update and stick, there's no real reason not to sandbox them.
sandboxie has a 64bit beta, and Avast as well as KIS have sandboxes that both work on 64bit i believe.
I'll have to look into that sbie beta then. I was under the impression that the sbie devs have given up on 64 bit.
Apparently not: http://www.sandboxie.com/phpbb/viewtopic.php?t=7014&sid=fb83b240353139c3bcf92c55d89e0f82
