Pinnacle Studio PCTV USB Limitation?

[bugeyes]

Hi
Some help please!

I have the Pinnacle Studio PCTV connected to my computer's USB port.
It has TV tunning, S-Video, composite video and audio inputs.
I'm trying to capture 480 x 480 TV images but with all the softwares
I tested (StudioPCTV Pinnacle supplyed,Virtual Dub,MyTV,FreeVCR,
and others) I'm limited to maximum 352 x 288 resolution images (we use Pal-M here).
Is this a limitation due to the Pinnacle equipment?
Am I using wrong filters/drivers?
Is the limitation due to my equipment?
-Athlon 1900+
-256 MB DDR 133 RAM
-W98
-40 GB IDE 5400 rpm quantum HD

Thanks