Windows 7 Recovery Drive Confusion: Can I Safely Delete Windows Old and Windows Folders?

Was running Vista Home 32 bit system. I always had problems with Vista so I wanted to upgrade to 7 ASAP. I never could get the upgrade advisior to run, I couldn't load 7 in as an upgrade either. I always got and error. I had all of my data backed up on a external so last night I did the custom install of 7. Everything went good and 7 loaded fine. Then I realized that when the screen showed the partitions on my computer I should have selected my C drive. I didn't select any drive so it loaded 7 on my Recovery D drive. I found this out when I started getting low disk space windows. I realized what I had done so I went back and reloaded 7 on my C drive and it works great. Here's the question, on my Recovery D drive I see the folder windows.old, I believe that is the old Vista program. Can I delete that? I also see a Windows folder, I believe that is 7 that I miss loaded on D the first time. Should I delete that?