I know I have a slot besides my integrated one but what is it?

I saved a report here

Computer:
Operating System Microsoft Windows XP Media Center Edition
OS Service Pack Service Pack 2
DirectX 4.09.00.0904 (DirectX 9.0c)
Computer Name CONRADS
User Name HP_Administrator

Motherboard:
CPU Type DualCore AMD Athlon 64 X2, 1800 MHz (9 x 200)
Motherboard Name Unknown
Motherboard Chipset Unknown
System Memory 1472 MB
BIOS Type Award (09/19/06)

Display:
Video Adapter NVIDIA GeForce 6150 LE (256 MB)
Monitor HP vs17 flat panel monitor [NoDB] (CNC618PJ6G)

Multimedia:
Audio Adapter Realtek HD Audio rear output

Storage:
IDE Controller Standard Dual Channel PCI IDE Controller
IDE Controller Standard Dual Channel PCI IDE Controller
IDE Controller Standard Dual Channel PCI IDE Controller
SCSI/RAID Controller SCSI/RAID Host Controller
Disk Drive Generic USB SD Reader USB Device
Disk Drive Generic USB CF Reader USB Device
Disk Drive Generic USB SM Reader USB Device
Disk Drive Generic USB MS Reader USB Device
Disk Drive WDC WD2500JS-60NCB1 (232 GB, IDE)
Optical Drive AW1964L YSQ647P SCSI CdRom Device
Optical Drive TSSTcorp CD/DVDW TS-H652L
SMART Hard Disks Status OK

Partitions:
C: (NTFS) 229457 MB (157724 MB free)
D: (FAT32) 8998 MB (434 MB free)
Total Size 232.9 GB (154.5 GB free)

Input:
Keyboard Enhanced Mulmedia PS/2 Keyboard
Mouse PS/2 Compatible Mouse

Network:
Network Adapter Compact Wireless-G USB Adapter (192.168.123.100)
Network Adapter NVIDIA nForce Networking Controller
Modem Agere Systems PCI-SV92PP Soft Modem

Peripherals:
Printer Fax
USB1 Controller Standard OpenHCD USB Host Controller [NoDB]
USB2 Controller Standard Enhanced PCI to USB Host Controller [NoDB]
USB Device Compact Wireless-G USB Adapter #3
USB Device USB Mass Storage Device

Problems & Suggestions:
Problem Disk free space is only 5% on drive D:.


any help would be great, thanks