I have a PC running with windows 7 ultimate 64 bit version with 4 gig Ram. I have a 320 gig hard disk , in which I have allocated 120 gig for windows 7, 100 gig for NY files(named ashwin in windows) and rest 80-90 gig partitioned but empty NTFS partition.Now where do I install Ubuntu so that windows and data is safe.

I got the option install with windows I selected it , it then shows select drive(SCSI1 (0,0,0) (sda) -320.1 GB ATA WDC WD3200AAJS-6) and allocate driver by dragging the divider below which shows 66.5gb and 59.3 GB respectively. Which one do I go with?

I clicked advance partitioning it shows five devices:

device   , type, m.point ,size.(mb), used(mb).........
/dev/sda1, NTFS,          104 ,      35 (windows 7 loader)
/dev/sda2, NTFS,          104752,    23604
/dev/sda3, NTFS,          125829,    10161
/dev/sda5, NTFS,          89382,     3221

when I checked size in properties it showed

name of drive according to windows,

            used.Gb,   free,   total.
ashwin,     10.2,      115.7,  125.8 
c drive,    23.6,      81.1,   104.8
new volume, 92.6mb,    89.3,   89.4

except mentioned everything in gigabytes.ignore the last dots. I want to install it in new volume or using that space how do I do it?

Explain in detail I'm a beginner.