ext1, ext2 are file systems like FAT32 and NTFS is in windows.
if you mean /sda1 /sda2 these are partitions on disk (sda1 = first parittion on first disk etc., sdb2 = second parittion on second (b) disk ).
i would say it would help if you used windows disk manager to create empty (unformatted) disk space and then during install install there.
you can also make a screenshot of your disk paritioning in windows disk manager and post here. someone might have some valuable avice to offer based on that.