My computer is acting weird after I installed the new hardware. I am not really good with computers so it's "possible" I screwed up the hardware installation but I DOUBT it because I was, 1., careful, and 2., following the directions (which, at least, I can do).

I installed new graphics cards so that I could play Call of Duty 4: Modern Warfare better. My original graphics card was a nVidia (GeForce, maybe?) 6150 SE. I upped it to a nVidia GeForce 8400 GS PCI Express.

My computer had an extra slot so I stuck the card in it without removing the original (which, due to my BAD PC skills, I could not identify). I was stupid the first time around and I installed the new video card software without removing the original. I uninstalled both softwares later and then reinstalled the newer one.

The problem: During Call of Duty 4: Modern Warfare gameplay, the computer can sometimes slow down A LOT, A LOT, A LOT (usually within 10 minutes of gaming). Even if I close the game, the computer is still slow for ~3 minutes after I shut the game before it returns to normal speed, which is moderately fast. This problem did NOT exist before the new hardware.

Here are the full specs generated by EVEREST:
(Keep in mind I have no idea what anything down below means, I just know how to generate a report via EVEREST).
(And if any more info is required, I won't mind generating another report).
(Thanks in advanced for the help!!!!!!!!!!).


--------[ Summary ]-----------------------------------------------------------------------------------------------------

Computer:
Computer Type ACPI x86-based PC
Operating System Microsoft Windows Vista Home Premium
OS Service Pack Service Pack 2
Internet Explorer 8.0.6001.18783
DirectX DirectX 10.0
Computer Name MATTH-PC
User Name Matthew
Logon Domain MATTH-PC
Date / Time 2009-06-09 / 19:20

Motherboard:
CPU Type DualCore AMD Athlon 64 X2, 2300 MHz (11.5 x 200) 4400+
Motherboard Name Unknown
Motherboard Chipset nVIDIA nForce 6100-4xx, AMD HAMMER
System Memory 3072 MB (DDR2-800 DDR2 SDRAM)
DIMM1: Samsung M3 78T2863QZS-CF7 1 GB DDR2-800 DDR2 SDRAM (6-6-6-18 @ 400 MHz) (5-5-5-15 @ 333 MHz) (4-4-4-12 @ 266 MHz)
DIMM2: Samsung M3 78T2863QZS-CF7 1 GB DDR2-800 DDR2 SDRAM (6-6-6-18 @ 400 MHz) (5-5-5-15 @ 333 MHz) (4-4-4-12 @ 266 MHz)
DIMM3: ProMos/Mosel Vitelic V916764K24QCFW-G6 512 MB DDR2-800 DDR2 SDRAM (6-6-6-18 @ 400 MHz) (5-5-5-15 @ 333 MHz) (4-4-4-12 @ 266 MHz)
DIMM4: ProMos/Mosel Vitelic V916764K24QCFW-G6 512 MB DDR2-800 DDR2 SDRAM (6-6-6-18 @ 400 MHz) (5-5-5-15 @ 333 MHz) (4-4-4-12 @ 266 MHz)
BIOS Type Award (05/02/08)

Display:
Video Adapter NVIDIA GeForce 8400 GS (256 MB)
Video Adapter NVIDIA GeForce 8400 GS (256 MB)
3D Accelerator nVIDIA GeForce 8400 GS
Monitor HP w2007 [20" LCD] (CNC816KRT8)

Multimedia:
Audio Adapter Realtek ALC888/S/T @ nVIDIA MCP61 - High Definition Audio Controller

Storage:
IDE Controller NVIDIA nForce Serial ATA Controller
IDE Controller NVIDIA nForce Serial ATA Controller
IDE Controller Standard Dual Channel PCI IDE Controller
Storage Controller ANU20NO7 IDE Controller
Storage Controller Microsoft iSCSI Initiator
Disk Drive ST336032 0AS SCSI Disk Device (335 GB)
Optical Drive ATAPI DVD A DH16A3L SCSI CdRom Device
Optical Drive WHQ S5MJCH27OH6 SCSI CdRom Device
SMART Hard Disks Status Unknown

Partitions:
C: (NTFS) 333835 MB (152172 MB free)
D: (NTFS) 9562 MB (998 MB free)
Total Size 335.3 GB (149.6 GB free)

Input:
Keyboard Enhanced Multimedia PS/2 Keyboard
Mouse Microsoft PS/2 Port Mouse (IntelliPoint)

Network:
Primary IP Address 192.168.1.47
Primary MAC Address 00-1F-C6-6E-AC-91
Network Adapter NVIDIA nForce 10/100 Mbps Ethernet (192.168.1.47)
Modem PCI SOFT Data Fax Modem with SmartCP

Peripherals:
Printer Adobe PDF
Printer Journal Note Writer
Printer Microsoft XPS Document Writer
Printer Samsung ML-1740 Series
Printer Send To OneNote 2007
Printer SnagIt 9
FireWire Controller AT&T/Lucent IEEE1394 FireWire Controller (PHY: Agere LFW3226/3227)
USB1 Controller nVIDIA MCP61 - OHCI USB 1.1 Controller
USB2 Controller nVIDIA MCP61 - EHCI USB 2.0 Controller
USB Device USB Mass Storage Device

DMI:
DMI BIOS Vendor Phoenix Technologies, LTD
DMI BIOS Version 5.13
DMI System Manufacturer HP-Pavilion
DMI System Product KQ422AA-ABA a6407c
DMI System Version
DMI System Serial Number MXU8200BZL
DMI System UUID 00F9739A-978E1310-AC2ABF3B-F639ED85
DMI Motherboard Manufacturer ASUSTek Computer INC.
DMI Motherboard Product NARRA3
DMI Motherboard Version 3.02
DMI Motherboard Serial Number MS1C84R52108231
DMI Chassis Manufacturer Hewlett-Packard
DMI Chassis Version Chassis Version
DMI Chassis Serial Number
DMI Chassis Asset Tag
DMI Chassis Type Desktop Case
DMI Total / Free Memory Sockets 4 / 0