If I remove my OEM Windows 7 partition, can I reinstall it on the same drive?

Ok, so I bought the OEM version of Windows 7, made a Bootcamp partition, and installed it. Works like a charm. The problem is, I can't do a lot of the stuff I would like to, because I didn't give myself nearly enough space on the partition--only 40 gigs, 20 of which are taken up by the operating system itself. So, I would like to expand the partition, or rather, create a larger one. So, the hardware will be unchanged, but it will be a different partition. I read that you can format an OEM-containing drive, and reinstall Windows, using the same product key or whatever. So, what I want to know is whether or not Windows will recognize the new partition as being on the same drive or not, and further, whether I'll even be able to reinstall it. I can afford another copy of 7, but I'd rather not spend money on something I already have.

Thank you for any support.