install new hdd

hi everybody.
I have installed windows 7 on a home built computer, thing is when it was xp,40 gb was ok,but since installing win 7 its telling me not enough disk space.
is it possible to tranfer the os to the newdrive by way of,the old drive is ide,
if I get a sata drive and plug in and powerup .is there anyway this can be done
because I only have a upgade win7 I cant start from clean install.
"Yeah"
john.

Welcome to Windows Seven Forums.

Check out this tutorial: Windows 7 Installation - Transfer to a New Computer

As a matter of interest, Win 7 32-bit requires a mnimum 16GB hard drive space, Win 7 64-bit requires a minimum 20GB hard drive space, but for a trouble-free install you should allow at least 40GB.