problem with reinstalling windows 7

so dont laugh at me, im new to the forums. So i dl w7 off my schools website and a burn it to a dvd+r. I install w7 but i clicked the wrong install and it made a file on my c drive saying "windows.old" (i think) which was everything from xp and my hard drive wasnt wiped out. I put that file into the recycle bin thinking that would help but some files were not able to delete properly. Since it didn't wipe out the hd like i wanted i reinstalled xp, which worked fine and it wiped out my hard drive like i wanted. I put in my windows 7 dvd back in thinking i could reinstall it with no problems and get what i wanted but now my w7 wont boot from the cd like it did the first time and when i try and run the setup i get this error message saying "windows was unable to create the required installation folder" with an error code of 0x80070017. I am wondering if i deleted some kinda folder that i cant get back or what.

I have tried new dvds and burning them at lower speeds. Sorry for the wall of text also.

i think the lowest i could burn at was 4x

it is a custom that i have had for years upgrading pieces when i can.

right now i have

motherboard-asus m4a78l-m

processor- AMD phenom 11 black edition multi core

graphics card- geforce 9400gt

hard drive- seagate 250g ide 7200.

ram-4gigs

and my boot order is
1 cd/dvd
2 hdd

what do u mean extra hd? only got the 250 in there

ya sry about that i meant 1. and then it will boot from number 2.

alright i am going to go try that see if it all works, thanks for the help