got my ex7000 today - love it!!

i havent got a proper hard drive sorted yet but thought i would try with an old 4gig usb stick i have

when i tried to record on it the picture went freezy and glitchy - is that just down to the memory stick ? when i stopped recording the piccy was tops again!

if so - can someone recomend an external usb drive manufacturer or place to buy from? dont need a massive one - about 120gig will do!!