any kind of lan card that connects to cat 5 cable is fine

OfficeMax frequently has a Belkin card that's $20 with a $10 MIR ($10 total AR). I got one a while back and was pleased with it. The rebate came (late), but some people have complained about OM rebates. In any case, if you're looking for cheap I would recommend that.

Unfortunately it's $30 now, but they have it on sale often: link

Assuming you don't want to look on Ebay or wait for a sale, here's the best deal I could track down:

SMC 10/100 Fixed-Port Fast Ethernet PC Card, $26.99, free shipping.

Here's a USB adapter:

Belkin USB 10/100 Ethernet Adapter, $22.99, shipped free

I would definitely recommend a plug in type like in the picture over one with a dongle. I had to replace 3 dongle cards from where the kids tripped over the cat5 cable.

Ok, getting a little better now.

SMC 10/100 Fixed-Port Fast Ethernet PC Card, $23.99 with free shipping

I haven't heard of this brand:

Trendware 10/100 PCMCIA 32-bit CardBus Ethernet Card W/ XpressPort, $21.99, free shipping

Man, searching buy.com is worse than pulling teeth.
Here's another:

LinkPort USB adapter, $16.63, free shipping

Hawking 10/100M CardBus Card, $15.99, shipping???

Now, if you're really desperate for a cheap solution...

Network adapter - serial RS-232, $9.39, shipping ???

EDIT: this last one was meant to be a joke, but in case that wasn't obvious, I thought I should clarify what this is. I believe it is just a serial port adapter for hooking up server consoles to a "console server". It's not really an ethernet adapter itself, but is used to hook up a serial port to a little box that itself has an ethernet adapter. So don't buy this!

If you're considering buying a USB network adapter make sure both the adapter and your computer supports USB 2.0. With USB 1.1 you're limited to a real world speed of 8mbps max. No big deal if you are just looking for Internet connectivity, but a very big deal if you're looking to network with other computers.

Better off going with a PC Card if your laptop has the available slot.

Here's a decent price on a well-known brand from a well-known store:

BestBuy has the D-Link Notebook 10/100 32-Bit PCMCIA Network Card for $29.99, and there is a $10 rebate.

Starting May 4, OfficeMax will have the D-Link Express 10/100 32-Bit Ethernet Adapter for $29.99 - $10 IR - $10 MIR = $9.99 AR.

Also starting May 4 at OfficeMax, if you want USB instead of PC Card, you can get the D-Link USB 2.0 Ethernet Adapter for $39.99 - $20 IR - $10 MIR = $9.99 AR.

i'm definitely getting the plug in type because the type with the attachment is what I broke on my laptop thanks for all the input everyone