Ouch! Now they want me to part with £129 for a Snow Leopard box upgrade. Think i might stick with Streamclip, or is there a cheaper way of doing this?

Snow Leopard alone is a bargain at just 25 pounds. Mac OS X 10.6 Snow Leopard - Apple Store (U.K.)

The Mac Box set at 129 pounds includes Snow Leopard, iLife '09 & iWork '09 which is also a bargain for what you get Mac Box Set - Apple Store (U.K.)

Nothing prevents you using the 25 pound Snow Leopard disk to upgrade Tiger except your conscience as Apple do not enforce their licensing by any technical means.

Thanks Nigel. Didn't realise i could do it for 25 quid. Can't see i'd have much need for the rest of the bundle.
Actually, i went out shooting this morning and captured everything into streamclip, which was highly efficient as always. Not sure i need the plug-in really, but at £25 i'll give it a go.