I was in same situation like you in June 2009. I went to every big dealers for Dell, Lenovo, HP and Acer.
Only Acer and Dell provided option to buy a laptop without OS. Dell machine was having FreeDOS, Acer had Linpus Linux. I had two choices at that time, Acer 4736 and Dell inspiron 15. Both were equal in configuration, in fact Acer dealer gave me USB mouse free of cost!
I opted for Acer 4736 because it was 5000/- cheaper. Linpus Linux was pathetic, so I promptly formatted the hard disk and opted for different distributions.
In last year, I have tried Fedora, Ubuntu, OpenSUSE, Sabayon, Debian, Arch Linux, Mint, even Slackware which I installed just yesterday.
Each hardware were properly detected under every Linux distro and I had zero trouble. Wifi was detected but couldn't test properly because I don't use Wifi internet.
So, I don't think you'll have any problems for above config with either Dell or Acer. My only concern is Ati card for which I think you should stick to major distributions.
But only choose between Acer and Dell, otherwise you won't get any no-OS option.