How to Upgrade Mac OS X 10.5.8 if iMac Is Running on Dual Boot?

Hi everyone!

I have an old iMac, dual boot - running both Windows XP and Mac OS X 10.5.8. I want to upgrade my Mac OS X 10.5.8 to at least Snow Leopard, because I can't even run youtube.com/download Google Chrome on my iMac right now (yes it is THAT old).

If i buy the Snow Leopard disk and install it, how will this affect the Windows XP? Will Snow Leopard work fine? Hoping to get some tips, just afraid that my iMac would stop working if I upgrade to Snow Leopard/ any other higher OS.

Thanks in advance for your time! :)