You may not be able to update first.
A lot of new malware blocks Windows and anti-virus/anti-malware updates.
My friend's Vista laptop won't get ANY
I've spent about 12 hours trying various fixes (including the MS ones) but it still won't update.
He's installed about 200 programs on his machine (although I suspect he probably only uses ~30 max) so he refuses to use the Recovery partition to reinstall his OS.
He also complains about how slow it is to boot up.
I looked at his Task Manager and he is running ~100 processes!