So when I got the TV in '01 (and knew nothing about HD) I saw 1080I and figured the TV was 1920x1080I.

I just saw under sharpness of TV thread that Tubes at most (Sony) get 1440x1080 while most are 800x1080I. So I looked up my old Tv specs and found that it does only 800 lines of resoution. So I guess my question is when using this TV as a monitor what should I set my resolution too?

Hitachi Ultravision 32" HDTV - Model # 32UDX10S
Features:
One Component Input
Two seperate Antenna Inputs
Three S-Video Inputs
Three Composite Video Inputs
HI-FI Audio Output
800 Line Horizontal Resolution
High Resolution Picture-In-Picture with Freeze
Full 1080i HDTV Capable with Set-Top Box
Universal Remote and Instruction Manual are included