WordPress MU

My blog (nativ27.com) is being flooded with spammers...
They are creating new blogs and making the titles 50+ lines long with 100+ links in the title of the blog...
I have probbally already marked over 200 blogs as spam, in the past few weeks.
Just today I have started to get them spamming the comment system.
Over 20, just today.

I am completely new wordpress, but how do i upgrade my wordpress mu??
is going to Site Admin, and then Upgrade enough??

and how do I get rid of all this spam?!

i have searched the forums, but the threads are flooded with so many post it hard to find the correct answers.
please please help me!

Oh boy, have I been there! I used two fixes which have almost eliminated splog signups on our site.

This thread http://mu.wordpress.org/forums/topic.php?id=5990 discusses a fix to the links in the title problem. The solution prevents html in the title.

However, I still had the problem with the extremely long list of keywords in the title, even without the html links, and it screwed up my page of latest blog listings. So I edited the signup and edit blog pages to limit how many characters could appear in the blog title, and that took care of that. Instructions are here http://mu.wordpress.org/forums/topic.php?id=6607 I added the same change to the edit blog file. I've hardly had any splogs sign up since adding this change.

Agreed. nativ27.com is running the 1.2.3 version of the mu software. The current release version is 1.2.5a with 1.3 currently in pre-release.

You may want to upgrade.

I have never upgaded before, and I dont want to mess anything up?
How do I do this step by step??
And what does Site Admin > Upgrade do??