Graphics Card Help

Hello.

I am recently considering buying either the
PNY GeForce FX 5200 128MB DDR AGP Graphics Card

click here

or the

PNY GeForce FX 5200 128MB DDR PCI Graphics Card

click here

My computer spec is as follows:

Entire System >
Manufacturer: Compaq
Model: Presario 5146EA 470019-259
Version: MODEL2

Processor(s) >
Model: AMD Athlon(tm) Processor
Speed: 1.30GHz
Model Number: 1303 (estimated)
Performance Rating: PR1733 (estimated)
L2 On-board Cache: 256kB ECC synchronous write-back

Mainboard and BIOS >
Bus(es): AGP PCI USB FireWire(1394)
MP Support: No
System BIOS: Compaq 786K3
Mainboard: Compaq 0708h
System Chipset: VIA Technologies Inc VT8363/5 KT133/KM133 System
Controller
Front Side Bus Speed: 2x 100MHz (200MHz data rate)
Installed Memory: 256MB SDRAM
Memory Bus Speed: 1x 100MHz (100MHz data rate)

Video System >
Monitor/Panel: COMPAQ MV740
Monitor/Panel: Default Monitor
Adapter: NVIDIA GeForce2 MX/MX 400

System Chipset >
Model: VIA Technologies Inc VT8363/5 KT133/KM133 System
Controller
Bus(es): AGP PCI USB FireWire(1394)
Front Side Bus Speed: 2x 100MHz (200MHz data rate)
In Order Queue Depth: 4 req(s)

Logical/Chipset Memory Banks >
Bank 0 Setting: 256MB SDRAM 7-1-1-1R 4-1-1-1W 3-3-3CL
Bank Interleave: 4-way
Speed: 1x 100MHz (100MHz data rate)
Multiplier: 1x
Power Down Mode: No
Fixed Hole Present: No

AGP Bus >
Version: 2.00
Speed: 66MHz
Current Data Transfer Rate: 4x 66MHz (264MHz data rate)
Side Band Enabled: No
Side Band Support: Yes
Fast-Writes Enabled: No
Aperture Size: 64MB

PCI Bus(es) >
Version: 2.10
No Buses: 1
No Bridges: 1
Speed: 33MHz
Multiplier: 1/3x

I am a hardcore gamer and want to upgrade my current system (without spending a fortune). I was hoping somebody could tell me which of the two cards would be the best to go for with my current spec, or graphics card upgrade reccomendations for my system.

Note: I will be upgrading the system from USB 1.1 to 2.0.

My main concerns at the moment is the speed of my AGP bus - I am not sure if it is 1x, 2x, 4x or 8x, and how to upgrade this.

Also, would I need to buy a new graphics adaptor for my PC?

And what speed can my motherboard manage (1x, 2x, 4x, 8x)?

Thanks in advance for any help,

Alien463