"my Windows 7 computer can't seem to read the disc(s)"
Explain to us what happens when you explore the contents of the CD/DVD.
You should be able to see and copy the files on the CD/DVD to your Windows 7 pc and your flash drive.
Is this a CD or DVD disc and has it been finalised? (finalised means 'closed', you choose this option in the burning program) In XP which program did you use to burn it?