Boot-up and install

If you try (don't try) to boot up from the gentoo 2007.0 cd (both live and minimal install), you'll notice that it won't find the ethernet device. That's because those cds were made upon kernel 2.6.19, and support for mcp67 controller was added on kernel 2.6.20. Gentoo team announced that 2008.0 cds will come along with kernel 2.6.24, so that won't be a problem if you're reading this after it's release. But, for now, you must use another live cd for that job (you can use any distro to install gentoo).
After wasting a cd (and a lot of time for download) with sabayon (again, don't try), I had success using Ubuntu 7.10 live cd. Use the safe graphical mode to boot (normal mode works too, but it turns into safe graphical on x startup). I didn't experience any problem with the hardware, but some people with slightly different acer models did with the hdd, so if it happens to you, try the 'all_generic_ide=1' boot parameter (Actually it may be needed if you set your disk mode to IDE on bios, mine is set to ahci).
I installed everything using a network with dhcp, and that saved me some time, but it's easy to configure the network by hand if needed, gentoo handbook explains everything. All you've got to do now is follow the handbook to do the installation.
When the time to install the kernel comes, use the 2.6.24 version (by now it's masked by ~, so you'll have to put it on the /etc/package.keywords file), earlier versions have a bug with the sata controller.
The drivers you'll have to add on the kernel at this time are the ahci for the sata controller (and ati/nvidia pata for the dvd drive), and forcedeth for the ethernet device. Also, set your sata controller mode to ahci on the bios.
Doing this shall avoid any problems with the installation and the following boot-up, but of course you'll have to configure the entire kernel to match your needs/preferences.
Now give the ubuntu cd to your girlfriend, I did and she liked =)