Let it.
They generally only release them once a month, and you can set it to automagically download and then leave them until you want to install them (since most of the time a monthly Windows Update seems to require a reboot for installation).
I'm running it on an Atom-based Netbook and it's fine.
If your startup begins to take longer as you add more apps, have a look at Soluto (one from the BKK Post!). It's quite a nice tool to see what's slowing down your start up and gives you control over what starts and when.
Soluto