internet connection wacky behind router

[Prophious]

ok so i have 2 computers on my network, one computer(mine) is kinda slower then my GF's Computer, anyways her computer is an i5 750 with 8 gb ram on win 7 ultimate 64-bit and her internet is really acting really weird, sometime it stalls others there are lag spikes... as you can see by the systems her computer should run the internet flawlessly but its the other way around... i seem to have no problem with the internet at all(mind you we use some of the same sites from time to time), now she is really close to the router so her cable is much shorter then mine (as listed below) so i have no idea what it could be, basically i'm just looking for a way to fix her connection

oh i forgot, the router is a dynex dx-e402, no wireless, and other devices on network(that are off most of the time) are and xbox 360 and and LG tv(purchased in june)


computers:
Mine:
msi k8n neo4-f motherboard
amd 64 x2 4400+ 939 pin
2gb ram
os drive: 80 gb (western digital, sata)
xfx brand nvidia 9800 gt
windows 7 ultimate 64 bit
800+ watt power supply(dont really remember the manufacturer, but i know its a good one)
connected to router though a single 100ft cat 5e cable, but only need about 25-30 ft

Hers:
Asus p7p55 lx
8gb(4 x 2gb) corsair memory(gotten though the online compatibly on corsair's website)
i5 750
os drive: 160gb (western digital, sata)
bfg brand nvidia 9800gtx+
windows 7 ultimate 64 bit
800+ watt power supply(dont really remember the manufacturer, but i know its a good one, not the same brand as above)
connected to router though a single 6ft-10ft cat 5e cable

 

[Hefemeister]

In order.

Have you tried a different cable? I would use yours since it is known to be good.

Different router port? again use yours as it is working well.

Reinstall lan drivers?

Tried a pci ethernet card if availiable?

 

[Prophious]

ok i'll try them.... i'll let you know what it was if it fixes it

btw do you think that having ports open on the router would fix it, there are a few ports open for my games and both of our torrent programs(none of these have any problems)

 

[J-Net]

Looks like you may be focusing a little too much on OS, ie layer 7 variables when it would be better to examine layers 1-3. Being that you have a physical connection to these, make sure the config on the router is the same for each port, verify the stats of your NICS are the same...find a difference in the networking between your machines.

Swap cables, ports, ect to test