Something that's not been said here so far is that Windows XP Service
Pack 2 (SP2) addresses many security issues -- regardless of opinions
regarding whether this attempts to make a silk purse out of a sow's
ear!  It's essential to keep any software updated, because this week's
theoretical problem is next week's new virus!

SP2 makes the Windows firewall active by default.  This is, however,
not really adequate because it only blocks inwards-coming traffic, such
as people [robots] scanning the net to find security gaps. You still
need a fuller firewall (such as the free ZoneAlarm) to also block
outwards-bound connections to the net -- which is what dodgy programs
such as spyware on your machine will be doing!  It also stops otherwise
useful programs from contacting the outside world unless you want them
to do so.  It's remarkable just how many try to do so.

Recent versions of ZoneAlarm (and other firewall programs) communicate
with the Windows firewall so that if you run ZoneAlarm (or etc.) the
Windows firewall doesn't start.  If you have an older firewall version,
upgrade it before [applying] the SP2 patch so that when you reboot you
don't get it and the Windows firewalls fighting.  This was reportedly
a major cause of problems encountered with the SP2 upgrade.

A sensible way of dealing with email via Outlook Express is to set the
security option to stop it loading or saving executable attachments.
This means that any virus (or otherwise) programs you may receive
simply cannot be executed -- the attachment is greyed out and nothing
happens if you click it.  You can, of course, opt to run those
attachments you want, and that's the point that up-to-date virus
protection becomes useful.

A SP2 fix of Outlook Express is to block the loading of website-based
images in emails, because these can be used to identify that you have
opened the mail and therefore that it went to a valid address.  Even
1-pixel images that you can't see will do this -- a really sneaky
example of what you can't realistically protect against simply by being
careful.

Julian Dyer