Need some computer help

[Trip]

I was running two computers on a router..a self built computer that ran L2 like a dream, and a crappy storebought computer that ran L2 like crap but i used for my buffer :)
Well earlier today a storm fried my main computer and my router, and turned my tv green, but that's another story :(

Anyway, here's my problem, and I can't figure this out:

I'm now playing L2 on my other computer, but its laggy and jerky as hell, and nothing I do will make it play any better. (it was always laggy and jerky when I used it for the buffer, but i figured it was cause of less ram)

Old comp had 1.8ghz processor, this one has 2.6.
Took the 1gb of ram out of the old one and put in this one.
Both comps had gforce 5500 256mb cards..old one has pci, this one has agp.
Old comp had a 32 gig hd that was very old, this one is a fairly new 60gb hd.
Old comp ran L2 perfectly in all high settings, never any lag at all.

So how come this one runs L2 like I'm tryin to play it on an atari? Its laggy as all hell, very jerky, runs like complete crap. Even in the lowest possible settings the fluidity of the performance doesn't improve a bit.

Any ideas?

[BelaLugosi]

you setup everything right ?

1.) BIOS . newest version? Bus speeds , AGP Speeds? Settings, and all that good stuff ?
2.) Drivers in Windows are at the newest Version? for Chipset, Graphics Card, etc etc.

3. Also check you NIC make sure your not loosing any packets to your router on the way , ports to&from @ Router.

[Trip]

Yea, got the newest drivers last night, defragged the system...there's no network lag at all, its all system lag, as if the computer is just too low end to handle L2's graphics, which I know isn't the case.

But I can't figure out why its running so poorly.