Any way to switch to Lubuntu without CD or flash drive?

  Hey all - currently I'm running the 'normal' Ubuntu 11.10 and it's running quite slowly so I am trying to switch to a lite version as I don't need all the bells and whistles anyway. My problem is I'm incredibly new to Linux and I'm having problems with either Brasero or my CD burner so every time I try to burn an iso it freezes after it finalizes the cd at "creating image checksum". Also, my computer doesn't seem to be able to boot from a flash drive. So basically I'm looking for suggestions on either how switch to Lubuntu or maybe keep my current one and speed it up by removing non-essentials. As I said earlier, I'm very new at this, so please talk to me like a child :) Thank you in advance!