macbook wont startup!

hello,

I was using my macbook the other night when it started running kind of choppy, it eventually froze so i was forced to power it off without shutting it down. Now it wont get past the grey startup screen. it sits there with the grey background and the apple, then the apple switches to a circle with the cross through it symbol. very frightening ha

i tried a pram reset as i saw that suggested somewhere but no help. i tried running a repair from the os disc within disc utitlity but it seems to get stuck saying "invalid node structure" and "invalid record count" and then it can't finish the repair

it is just within the 1 year warranty so i will likely take it in on tuesday, but if anyone has any other suggestions or ideas what the problem might be it'd be greatly appreciated!
thanks!
~Gordon

p.s. is there anyway to backup what is on my drive before i take it in for repair from the os disc screen?

In my blog are instructions for "firewire target mode". If you have another Mac or a friend with another Mac, then it's possible to try to use your Mac as a FW harddrive to that Mac and backup that way. Described in my blog, url in signaure.