I wanna partition more space for Ubuntu! (dual booting w/ Windows 7)

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http://askubuntu.com – So, I bought this computer recently, and immediately dual-booted Ubuntu 12.04 LTS with it. The other day, unfortunately, I ran out of the mere 20 or so gigs alloted to me (out of about 700). I'd like to repartition more space, but I'm running into a bit of trouble. I found this instruction: How do I remove windows but keep Ubuntu? but ran into problems when it came to booting from the flash. It's just not recognizing the flash in my boot menu. I know that the flash works, I should add, because my girlfriend just used it twice for both of her machines. I'm sure that it's now obvious that I am (HowTos)