Security updates or virus definitions?

Security updates or virus definitions? What first?

I am connecting a Win2k PC, stand alone, to the Internet for the first time. ADSL.

I have installed SP4 and bug fixes for Win2k up to April 2005. Also MS05-39 (zotob). IE6 SP1 and MS05-052 (cumulative for IE).

I have Trend Micro Internet Security with a soft Fire Wall, but not the latest definitions.

Where do I go first, Windows Update or Trend Micro?

I would have liked a router also, but I do not have it.

Regards, Gunnar Klevedal