IBM T21 c drive only 10gbs max???

Can someone tell me why I only have 10gbs and what I need to get more?

Computer
Operating System Microsoft Windows 2000 Professional
OS Service Pack Service Pack 4
Internet Explorer 6.0.2800.1106 (IE 6.0 SP1)

Motherboard
CPU Type Mobile Intel Pentium IIIE, 600 MHz (6 x 100)
Motherboard Name IBM 26476BU
Motherboard Chipset Intel 82440BX/ZX
System Memory 384 MB (SDRAM)
BIOS Type Phoenix (10/17/00)
Communication Port Communications Port (COM1)
Communication Port Printer Port (LPT1)

Storage
Disk Drive IBM-DJSA-210 (10 GB, 4200 RPM, Ultra-ATA/66)

Partitions
C: (FAT32) 9580 MB (646 MB free)

Problems & Suggestions
Problem Disk free space is only 7% on drive C:.