Can i install windows7 on an old hard drive with alot of data and no previous operating system, without deleting or harming that data (many folders of office files, music, pics and so forth)?
You can't install Windows on the same partition as the data without wiping out the data.
But you could do this:
Shrink the partition containing the data if it isn't full.
That would create "unallocated space".
Then make a new partition from that unallocated space.
Then install Windows to the new partition.
Whether it's practical in your case depends on full the drive is. If it's a 500 GB partition, with only 10 GB free, you couldn't shrink it enough to hold Windows.
But if it's a 500 GB partition with only 200 being used, you could shrink by 300, make a 300 GB new partition, and install to it.
But-----fiddling with partitions has some risk to the data. You are best advised to back the data up to some other drive first.
Best tool for the job is probably Partition Wizard.