As long as you are logged into a secure site, and only accept Emails from a known source, there should (theoretically) be no problems.
My normal procedure now, is to load operating system, whist machine is off line, bung on XP SP2 (that takes care of a bulk load of updates).
Next is the MB software etc.
Next up is A/V and Firewall, then internet connection.
Then update all.
The best bet then, is to backup the lot, so that you can reinstall in one hit.
All other software is then loaded and tested one at a time (I use more than one drive/partition. The C: drive is only for operating system plus essential software.