ati tv wonder 2.0 usb

hi gang

im having a problem installing this unit.i get messages saying if i install it might work well on this computer do u still want to continue.
when i get it installed the tv part works ok but when i try to watch a video tape its jerky and out of sinc.what can i do about it if anything?
i have a dell demension 1100 on a xp system.

coonsanders