Just curious, do you have a core duo processor or better?

Minimum requirements for Photobooth Effects

Intel Core Duo processor or faster.
At least 128 Kbps upstream and downstream bandwidth.
Minimum requirements for Backdrop Effects

Intel Core Duo processor or faster.
iSight camera, external USB Video Class (UVC) camera, or Firewire DV camcorder with fixed focus, exposure and white balance.
At least 128 Kbps upstream and downstream bandwidth.
Minimum requirements for Screen Sharing

All Macs that support Mac OS X 10.5 Leopard.
At least 128 Kbps upstream and downstream bandwidth. At least 300 Kbps is recommended.
Minimum requirements for AV Recording

All Macs that support Mac OS X 10.5 Leopard. Resolution and frame rate may vary based on the computer.
At least 128 Kbps upstream and downstream bandwidth.
Minimum requirements for iChat Theater

Side-by-side view is available on all Leopard-compatible Macs capable of participating in a multiway video conference.

Side-by-side Replacement Mode
Sender System required Dual 1 GHz G4, any G5, any Intel All Leopard-compatible Macs are supported
Bandwidth required 384Kbps up/down, 900Kbps up to send 640x480 resolution Keynote files 128Kbps up/down, 900Kbps down to receive 640x480 resolution Keynote files
Receiver System required 1 GHz G4, dual 800 MHz G4, any G5, or any Intel All Leopard-compatible Macs are supported
Bandwidth required 128Kbps up/down 128Kbps up/down