Thanks for pointing out the GPU check-box it helped somewhat for me. I have the 7950GT 512MB video card and Vegas is still jumpy with HDV files. I do run the raw .m2t files as they work terrific without effects. Very smooth. Any other tweaks I could try? :)

A 7950Gt will not be 100% smooth using m2t hdv. I run an 8800 and altho it is very good it is not silky smooth.

the first thing I woudl try is using cineform aspect hd.