Step 1: Make sure you have Debian Backports in your /etc/apt/sources.list
deb http://backports.debian.org/debian-backports squeeze-backports main
Step 2: Install the kernel for your architecture
For 64 bit:
apt-get install -t squeeze-backports linux-image-3.2.0-0.bpo.4-amd64 firmware-linux-free
For 32 bit:
apt-get install -t squeeze-backports linux-image-3.2.0-0.bpo.4-686-pae firmware-linux-free