Upgrade OS X with Windows already installed using Boot Camp - will it break anything? I've got a late 2010 MacBook Air that came with OS X 10.6.6 installed; I have never upgraded it to 10.6.8 Snow Leopard or to 10.7 Lion. 

I dual boot with Windows 7 installed using boot camp. I use rEFIt as my boot loader.

Disk Utility in OS X shows:


Macintosh HD is partition 2 
partition 3 is an empty FAT partition
Windows HD is partition 4


I don't know why partition 1 doesn't show up there. In Windows under Disk Management it shows up as 200 MB (GPT Protective Partition)

When booting, rEFIt gives me these options:


Boot to Mac OS X
Boot to Windows on Partition 4


If I upgrade OS X to Lion, is there any risk of breaking my Windows install, messing up my Windows partition or the boot loader or anything like that?
If you're doing just a straight upgrade and not a complete rebuild, then it should be absolutely fine. OS X upgrades are aware of other partitions so it shouldn't break anything.

By the way, I know this is not question, but I used to use Boot Camp, but find Parallels a much better experience overall. Disclaimer, I'm a .net developer.