partitioning recommendation/advice needed

Hello all,

I have a 320 gb hard drive, and it has Windows 7 already installed. What I would like to is to install ubuntu besides windows (I will shrink/spare windows to 20 gb). But I also would like later to install other distros such as FreeBSD and Fubuntu for testing. Right now, I am thinking to partition my hard drive like this:

Windows -- 20 gb
/ (root) Ubuntu -- 25 gb
home -- 20 gb
swap -- 2 gb (the same as RAM)
Data (music, videos, docs/ebooks) -- 120 gb
?[maybe for docs/ebooks I would do a separate partition -- 10 gb]?
for two other distros, 15 gb each -- 30 gb
--------------------------------------------
this sums up to -- 227 gb

I still would have about 100 gb free space! Doesn't look like an efficient partitioning to me. What would you guys recommend as more efficient??

By the way, for Data, I don't think I will need to fill up more than even 100 gb. For docs/books, yes, I have many files to fill up at least half of 10 gb.

I would really appreciate your advice.
Thanks