Thanks for the input Jim. I've bit the bullet and ordered the HP. I've read lots of good reviews of it (from users as well as 'reviewers') but very little on the Dell hence my decision.
Low latency isn't particularly important regarding the audio side as I'll be monitoring direct from my ZED-R16. For what little soft synth work I do I can do that in my studio as will the mixing stage. If it turns out I can do that on the HP that'll be a bonus but not essential.
I'm getting more and more live recording work. My battered old Toshiba Satellite works perfectly well for that purpose *if* for some reason the HP won't but of course it'd be easier if it does work.
Audio with firewire on laptops seems pretty much a dead end but I never envisaged recording live away from the studio when I bought the ZED which is great on my DAW. Not that it is important to me but it'll run an ASIO buffer of 64 samples with a reported roundtrip latency of 5.8 msecs. It'll run all day like that without problems/drop out etc. As I monitor through the board though it's pretty much irrelevant to me.
My main use for the laptop will be for screen captures for video work which is why I need the higher resolution. I can also do much of that in the studio but it'll be extremely convienent not to mention more efficient for me, if I can carry on with the video side of things while I'm away from the studio, and for video the HP gets rated quite well.
I'll post my findings on how it works when I get it set up. It may be helpful for someone else. I've found very little audio based information for it so any I add may be a bonus for others.
Thanks again to everyone for all the input and comments.