PC performance problem , urgent help needed

Dear Sirs,
I have had upgraded my PC using the following specifications which should work efficiently on any thing, it worked quite fine and well at first ,but then I had installed another Hard drive which is western digital as shown below and I had a bad type PSU of 300W in the first place ,after some time I noticed some instability and slowness in performing specially if I install a game and run another program like playing a video ;it plays so slow and disconnecting , then I got Huntkey 500W PSU thinking it might be the reason but still the same slowness problem ,is it some PC component got consumed or exhausted? or its components compatibility problem or any suggestion please?
Taking into consideration that my 4G RAM bus speed is 667 MHz and the processor front side bus is 1333 MHz , so the FSBRAM is 1:1

please help me diagnosing the reason of this problem and solving it urgently.

Many thanks
Sam
SiSoftware Sandra

System
Host Name : HAPPINES-D71044
User : Happiness
Workgroup : WORKGROUP

Processor
Model : Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz
Speed : 3GHz
Cores per Processor : 2 Unit(s)
Threads per Core : 1 Unit(s)
Type : Dual-Core
Internal Data Cache : 2x 32kB, Synchronous, Write-Thru, 8-way, 64 byte line size
L2 On-board Cache : 6MB, ECC, Synchronous, ATC, 24-way, 64 byte line size, 2 threads sharing

System
System : Gigabyte Technology Co., Ltd. EP43-DS3L
Mainboard : Gigabyte Technology Co., Ltd. EP43-DS3L
Bus(es) : PCI PCIe USB
Multi-Processor (MP) Support : No
Multi-Processor Advanced PIC (APIC) : No
System BIOS : Award Software International, Inc. F8
Total Memory : 3.25GB)

Chipset
Model : Giga-Byte ??? (2E20)
Front Side Bus Speed : 4x 333MHz (1.33GHz)

Video System
Adapter : NVIDIA GeForce 8500 GT (1GB DDR2, PCIe 1.00 x16, PS 3.0, VS 3.0)

Physical Storage Devices
MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache) : 233GB (C (E (F (G (H (I (J
WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache) : 233GB (D (K (L (M:) (N:) (O:) (P:)
HL-DT-ST DVD-RAM GH22NP20 (ATAPI66, DVD+-RW, CD-RW, 2MB Cache, 192kB Flash) : N/A (Q:)
HL-DT-ST DVDRAM GSA-H42N (ATAPI66, DVD+-RW, CD-RW, 2MB Cache) : N/A (R:)
TYLW NCDQVOTMJ (SCSI, BD-R, HD-DVD-R, DVD+-R-DL, CD-R) : N/A (S:)

Logical Storage Devices
Windows XP (C:) : 53GB (NTFS) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(E:) : 25GB (FAT32) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(F:) : 34GB (FAT32) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(G:) : 29GB (FAT32) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(H:) : 29GB (FAT32) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(I:) : 29GB (FAT32) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(J:) : 33GB (NTFS) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache

(D:) : 49GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(K:) : 34GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(L:) : 34GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(M:) : 34GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(N:) : 34GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(O:) : 23GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(P:) : 24GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
CD-ROM/DVD (Q:) : N/A @ HL-DT-ST DVD-RAM GH22NP20 (ATAPI66, DVD+-RW, CD-RW, 2MB Cache, 192kB Flash)
CD-ROM/DVD (R:) : N/A @ HL-DT-ST DVDRAM GSA-H42N (ATAPI66, DVD+-RW, CD-RW, 2MB Cache)
CD-ROM/DVD (S:) : N/A @ TYLW NCDQVOTMJ (SCSI, BD-R, HD-DVD-R, DVD+-R-DL, CD-R)

Peripherals
LPC Hub Controller 1 : Giga-Byte LPC Interface Controller
LPC Hub Controller 2 : Giga-Byte SMBus Controller
Audio Device : Giga-Byte HD Audio Controller
Serial Port(s) : 1
Parallel Port(s) : 1
USB Controller 1 : Giga-Byte USB UHCI Controller #4
USB Controller 2 : Giga-Byte USB UHCI Controller #5
USB Controller 3 : Giga-Byte USB UHCI Controller #6
USB Controller 4 : Giga-Byte USB EHCI Controller #2
USB Controller 5 : Giga-Byte USB UHCI Controller #1
USB Controller 6 : Giga-Byte USB UHCI Controller #2
USB Controller 7 : Giga-Byte USB UHCI Controller #3
USB Controller 8 : Giga-Byte USB EHCI Controller #1

Printers and Faxes
Printer : Microsoft XPS Document Writer (600x600, Colour)
Printer : Microsoft Office Document Image Writer Driver (300x300, Colour)
Printer : HP Deskjet F4100 series (1200x1200, USB, Colour)
Printer : Adobe PDF Converter (4000x4000, Colour)

Scanners and Cameras
Camcorder : Vimicro USB PC Camera (ZC0301PL) #2 ()

Network Services
Network Adapter : D-Link Wireless 108G DWA-520 Desktop Adapter - Packet Scheduler Miniport (Ethernet, 54Mbps)
Network Adapter : TechniSat DVB-PC TV Star PCI - Packet Scheduler Miniport (Ethernet, 100Mbps)
Network Adapter : Realtek RTL8168C(P)/8111C(P) PCI-E Gigabit Ethernet NIC - Packet Scheduler Miniport

Power Management
Mains (AC) Line Status : On-Line

Operating System(s)
Windows System : Microsoft Windows XP (2002) Professional 5.01.2600 (Service Pack 2)
Platform Compliance : x86

Logical Storage Devices
Windows XP (C) : 53GB (NTFS) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(E) : 25GB (FAT32) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(F) : 34GB (FAT32) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(G) : 29GB (FAT32) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(H) : 29GB (FAT32) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(I) : 29GB (FAT32) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache)
(J) : 33GB (NTFS) @ MAXTOR STM3250310AS 250GB (SATA300, NCQ, 8MB Cache

(D) : 49GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(K) : 34GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(L) : 34GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(M) : 34GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(N) : 34GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(O) : 23GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
(P) : 24GB (NTFS) @ WDC WD2500AAJS-00B4A0 3.5" 250GB (SATA300, 7200rpm, NCQ, 8MB Cache)
CD-ROM/DVD (Q) : N/A @ HL-DT-ST DVD-RAM GH22NP20 (ATAPI66, DVD+-RW, CD-RW, 2MB Cache, 192kB Flash)
CD-ROM/DVD (R) : N/A @ HL-DT-ST DVDRAM GSA-H42N (ATAPI66, DVD+-RW, CD-RW, 2MB Cache)
CD-ROM/DVD (S) : N/A @ TYLW NCDQVOTMJ (SCSI, BD-R, HD-DVD-R, DVD+-R-DL, CD-R)

What in the world is all of this? Either I am not understanding this correctly, or do you actually have your drive(s) partitioned into this ridiculous mess?