virutalization questions

Hi, my current security setup:

Comodo Internet Security with HIPS+ enabled
EMET 2.x (max. security, most programs added)
UAC at max level (with password protection) while using a standart user
Norton DNS
Hardware Firewall (soon DD-WRT)

I now thought about using sanboxie and do the following:

for each program (mail,browser,messengers) create an own sandbox. This should prevent that any password-stealer gets access to them and steals my data? More over, if i should open and infected mail/link/messenger exploit, nothing can happend to the rest of the system?

Is that theory correct? Will it cause performance loss? Or am I secure enough with UAC @max level + comodo av/fw/hips ? Normally UAC & Comodo should restrict access on but it could happen that i still allow a program to be runned as admin (this would allow them everything). However, sanboxie (or some other virtualization program) would “hide” the browser/mail/etc from the normal system… so it cant be stolen?

Thankss

@edit:
I’m on win7 x64 with a dual core 2 duo 2,53ghz,4gb ram laptop… 80gb SSD + 1tb HDD.
Sandboxed stuff would be on SSD.