Zonet ZEN3301E Network adapter - PCI

Zonet ZEN3301E Network adapter - PCI: "Data Transfer Rate 1 Gbps
Features Wake on LAN (WOL), half duplex mode, full duplex mode
Compliant Standards IEEE 802.3, IEEE 802.3u, IEEE 802.3ab
Expansion / Connectivity
Interfaces 1 x network - Ethernet 10Base-T/100Base-TX/1000Base-T - RJ-45
Compatible Slots 1 x PCI
Manufacturer Warranty
Service & Support 1 year warranty
Service & Support Details Limited warranty - 1 year
Universal Product Identifiers
Brand Zonet Technology
Part Number ZEN3301E"

I am trying to figure out why the card above does not completely fill the slot on the PCI slot on the motherboard having the specifications below:

ASUS
M4N68T-M V2 Socket AM3 630a mATX Motherboard

Introducing the ASUS M4N68T-M V2 motherboard: The M4N68T-M V2 features nVIDIA GeForce 7025 / nForce 630a chipset and supports dual channel DDR3 memory up to 1800 MHz. Protect 3.0 Technology provides low-radiation shielding which effectively reduces 50% more radiation than other brands. ASUS Anti-Surge Protection guards your system from damage caused by unstable voltage. ASUS system level energy saving technology, EPU- 4 Engine intelligently reduces power consumption. ASUS Turbo Key provides a one-touch performance boost for uninterrupted game play or work. Intelligently unlock true core performance with Core Unlocker via a press of a button or a simple touch of the hot key"no need to enter the BIOS. Lastly, ASUS M4N68T-M V2 uses all solid capacitors to ensure stability and longer lifespan.

General Features
Features	Core Unlocker - Unleash True Core Performance Intelligently; Turbo Key - Touch-N-Boost! No more lag! Anti-Surge Protection; Dual channel DDR3 1800(O.C.); 100% All High-quality Conductive Polymer Capacitors
Overclocking Features	Turbo Key - ASUS Turbo Key allows the user to turn the PC power button into an overclocking button. After the easy setup, Turbo Key can boost performances without interrupting ongoing work or games - with just one touch!!
Chipset
North Bridge	NVIDIA nForce 630a
BIOS	AMI BIOS 8Mb Flash ROM PnP, DMI2.0, WfM2.0, SM BIOS 2.5, ACPI 2.0a
CPU Supported
Socket Type	AM3
AMD CPU Support	Sempron 100 series Phenom II X4 Phenom II X3 Athlon II X2 Athlon II X3 Phenom II X2 Athlon II X4 Phenom II X6
Front Side Bus	2000MT/s 1600MT/s
Memory
Memory Type	DDR3
Memory Speeds Supported	DDR3-1800 (O.C.), DDR3-1600 (O.C.), DDR3-1333, DDR3-1066
Memory Slots	2 x 240pin DIMM
Max Memory Supported	8GB
Memory Channel Support	Dual Channel
Storage Controllers
PATA	1
SATA 3Gb/s	4
SATA RAID	0/1/5/10/JBOD
Video
Onboard Graphic Chipset	NVIDIA GeForce 7025
Audio
Audio System	VIA VT1708S
Audio Channels	8-Channel
Networking
LAN Chipset	Realtek RTL8211CL-VB
LAN Speed	10/100/1000Mbps
Expansion Slots
PCI Express x16	1
PCI Express x1	1
PCI	2
Back Panel Ports
PS/2	2
Serial 9-pin	1
Parallel 25-pin	1
VGA 15-pin	1
USB 2.0	4
LAN RJ-45	1
Audio Ports	3
Internal I/O
USB	3 x USB 2.0 Headers (supports 6 additional USB ports)
Other I/O	Front Audio Header Front Panel Header S/PDIF-Out Header 1 x CPU Fan Header 1 x System Fan Header
Power
ATX Power Connector	24-pin
ATX12V / EPS 12V Connector	4-pin
Physical Specifications
Form Factor	mATX
Dimensions (WxD)	9.6" x 8.2" (244mm x 208mm)
What's in the Box
What's in the Box	Motherboard, User's manual, I/O Shield, 2 x SATA cables, 1 x UltraDMA 133/100 cable, Driver/Utility CD (Drivers, ASUS PC Probe II, Anti-virus software (OEM version), ASUS Update)

The issue is this, and here is my theory which I will try to research:


1) The older cards I swapped out of computers I took apart completely fill up the slot of the motherboard.


 The new Zonet Zen3301E card says its compatible with Windows 7, so my conclusion is that it is merely a backwards compatibility issue with the older type of PCI cards. Additionally the PCI slot on the motherboard is designed to accomodate many different types of accessories so it probably can accomodate several different types of cards.