I installed Kubuntu 10.10 on my daughter's new HP dv6tse a few months back. I liked the machine quite a bit, but CatKiller's comment about partitioning is spot on. HP drives come with all four primary partitions in use; none of them is an extended partition. If you go the HP route, here's what I'd recommend. You'll need a USB drive or a network share to create the backups described below.
1) Boot from the Ubuntu disk, then open a terminal and use dd to create an image of the first partition onto the backup device. That holds the Win7 replacement disks. If you use a USB drive, the command would be:
assuming the USB drive is mounted as /media/disk.
dd if=/dev/sda1 of=/media/disk/win7.img
You can only make one set of the Windows disks, so making a copy of the partition first will get around this limitation. If you ever need another set of disks, you can restore the original partition from the image with dd.
2) Now boot Windows and use HP's utility to make yourself a set of Win7 DVDs.
3) Boot again from the Ubuntu CD. Use "fdisk -l" to list all the partitions; you'll need that in a moment.
4) Use dd to make an image of the fourth partition (/dev/sda4); we'll be restoring it again soon.
5) Use fdisk to delete partitions 3 and 4, then create a single extended partition that uses all the unallocated space.
6) Use fdisk to create a new logical partition in the extended area to hold Windows and mark it as NTFS. Make sure you leave enough unallocated space to hold Linux and any files you might put there. My daughter's machine had a 640 GB drive; I think I allocated about 100 GB to Linux.
7) Use fdisk to create a new logical partition in the extended area that has the same number of cylinders as the old partition four did. Then use dd to copy back the image of that partition you created in step four. (I think this one should also be marked for NTFS, but I can't remember for sure, and the computer is now hundreds of miles away at college.)
8) Use fdisk to create a new logical partition in the remaining unallocated space into which Linux will be installed. Mark it for Linux.
9) Re-install Win7 into the NTFS partition you created in step six using the disks you made in step two. You'll be pleased to discover this version of Win7 has a lot less additional crap compared to the factory installation.
10) Install Ubuntu into the Linux partition created in step eight.
If you buy a machine with an ATI Mobile Radeon as we did, you may need to upgrade the BIOS as I describe here.
I don't recall which wifi adapter this machine had, but it was recognized by Ubuntu during installation.