Ubuntu broken after kernel update?

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Hi, after upgrading my dualboot machine (XP and Ubuntu) from Xp to Windows
Seven, it lost the ability to dual boot. Nevermind, with EasyBCD I
reconfigured the Windows 7 bootmanager to dual boot Windows 7 and Ubuntu.
It's now using Windows Seven bootmanager instead of Grub. Sofar so good.
After a couple of days, Ubuntu 9.04 warned it needed to update the kernel.
Then the update manager asked me whether i wanted to let the manager update
my menu.lst (it never did that before). I said no, keep the old one (on
hindsight, I wonder what got into me .

Now, Ubuntu will not boot anymore. After the initial Ubuntu startscreen I
see a lot of text scrolling, and then: "Target Filesystem does not have
/sbin/init", and a prompt for "Initramfs". When I exit that, it says
something like "operating system panic".
The latest kernel in the menu.lst is 2.6.28-15 generic.

Any help immensely appreciated!

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Sure the best help we can give you is to wipe that crummy Ubuntu off your
system and stick with Windows 7. Ubuntu is for DOPES.