I need to reallocate my space

[EinsDrei]

Can I expand things without loosing my data.
Lets see I got
/
/boot
and swap

So therefore I got like 7 gigs (yes) of space available to me.

Now, i happend to like Gentoo a little bit more then I thought, so I have 20 gigs of free space that once belonged to a windows os.
How can I use those.

I thought of just formatting them in XFS and put it under /home, since I don't have separated folders.
Also I could think of putting 10 gigs in /usr and 10 in /home.

But there is a problem for me. I do have my /home and /usr right now. Can I just add extra mountpoints in fstab and he will ignore the old /home and /usr, or do I have to rename them (cause I want to keep the data somewhere, especially /usr) or something completely different?

Since I don't really have to "resize" a partition, but simply to add partitions, I figured it is possible.

Also, I heard XFS is a enormous Speed-Up for /home
So if it was wise to use XFS, could u also guide me through the changes I have to make?
I am running 2.6.4, cause I don't know how to update my kernel (yet) without hurting my system.

Anyway, as you can see space is rare, so I might not use XFS for /usr, but for /home I guess it would be fine.
Decisions, decision.

[EinsDrei]

come on guys you can figure something out