Mac...? Pc...? Oh the humanity!

So I need to upgrade my work station and I’m trying to decide what route to go.

Option 1# Probably around $800.
Stay PC. Upgrade to 3x 19" Flat Panels.
Upgrade an old workstation with ram and HD space

Option 2# Probably around $2000
G5 Workstation
2x 19" Flat Panels

Option 3# Probably around $1500
G4 Workstation
2x 19" Flat Panels

Option 3# Probably around $1500
G5 iMac 20"
1x 19" Flat Panel

Any thoughts?