Problems connecting to wireless network(laptop)

[yermolovd]

Hello. I finally decided to make a post after long and unsuccessful research.

I have the following hardware:
Linksys WRT54GS router
Main home pc, connected to router with wired connection.
Another home pc, connected to router with wireless Linksys card. (no problem here)
Toshiba Tecra M2 with Intel 2100 3B adapter.

Problem:
I can not connect to my wireless network with the laptop.
Funny thing: I used to be able to connect with this same laptop, before I had to reinstall my Windows. I tried installing three different versions of Windows XP, XP+SP1, XP+SP2.. and Windows 2000. I could not get my wireless connection to work.
Also, I tried resetting the router. I disabled any security options: no encryption, just open access. Also updated the firmware for my router. I have another computer, mentioned above, and I do not have any problems connecting to the network with it. I tried different(older) versions of drivers for wireless laptop card and still nothing.
I used Windows own soft to configure network access. After that I tried Intel(Pro)Set software to connect, no luck. I used NetStumbler to detect the network: network is clearly visible and has good strenth (obviously, as I sit half a meter from the router). I disabled Windows firewall, still nothing. I referred to user manual, where it stated that wireless cards might be switched off, tried the shortcut to turn on/off the card, nothing. I used Toshiba's software that manages wireless connections: the wireless card is always on, no problem here. I installed the same exact Windows it used to work with, still nothing.

So, I mean, what else do I need to check/do? I feel that soon I'm prety much going to be ready for mental hospital treatment. I've already spent about 5 days on this in total.
I hope I do not end up buying exterenal wireless card for my laptop.

I might have forgotten something in this post, but prety much I've tried everything mentioned on various forums on the internet. And I don't see too many people having the same issues like I do.

Any ideas would be appreciated. Thank you.

[Funky Freddy]

Have you checked that the ariel that attaches to your internal card is still connected?

[yermolovd]

I'm not sure where that ariel is. I checked the manual, nothing mentioning it. I just tried setting up ad-hoc network between my other pc with wireless card and this laptop. They both connected no problem. This leads me to think something is wrong with my router. Hmm.