Hi mate,
Go to device management in Cubase and look for VST audio system, If you are using the TI as your soundcard you should see it listed in the drop down box, either Virus TI ASIO or VIRUS TI core audio. Beside that there should be a button saying Control Panel, Click that and select 128 for your buffer size.
Taken from the Cubase Manual
You can check the latency for your audio hardware in
the Device Setup dialog (VST Audio System page).
The input and output latency values are shown below the ASIO Driver
pop-up menu. For live VST Instrument playing, these values should ideally
be a few milliseconds (although the limit for “comfortable” live playing
is a matter of personal taste).
Cubase 5 Manual
thank you so much 
jsut wondering,oncei changed from 256 to128 in the control panel,whate xactly will it effect? the entire tracks or just the virus?
thanks again for the help
This is the size of the last buffer before the audio goes to the soundcard circuitry and DAC-s. It is compensated so all the meters and indicators you see on the screen are in sync. It only matters when you are playing live, as scientificharmony said.
No, the audio qulaity will be the same.
ok great,thank you very much
