I have 2 HDD, 1st si 40GB with 10GB allocated for windows, another 10GB ready for Ubuntu, the rest is empty.

My question is, the 2nd hdd 160GB contains most of my personal data, i wonder what impact will be if i boot ubuntu and try to use the 2nd hdd?

i understand it's a stupid question, but it's my first in ubuntu, please advise. thanks!