Really slow wireless connection

OK so I have a laptop with 802.11g wireless built in
Connect to the interet through a wireless router/modem combination
Recently I've been getting really low connection speeds, in the region of about 3kb/sec
Sometimes the connection speed will be normal, other times it will be really slow
It was fine before, but it's been like this for about a week
I didn't change anything to make it do this, and I've tried to fix it with no success
Ca anyone here help me out?

How is your WLAN configured?

What sort of info do I need to supply here?
Don't know what else I need but here's some info, a bit of a shot in the dark
Router: Linksys OfficeConnect ADSL Wireless 11G Firewall Router (3CRWDR100A-72)
Encryption: WPA-PSK, TKIP
WAN Connection type: PPOA
Wireless Mode: 11G only
Wireless card in laptop is a Ralink 802.11G MiniPCI Wireless Network Adapter according to Device Manager
Using Windows Zero Configuration tool to manage wireless connection
All IP addresses, DNS, default gateway etc configured correctly

What happened before it slowed down? Did you move it further away from the Router? How far away is it from the router?

Did you try setting the power output setting to 100%? Not sure where you can do this using Windows Zero Wireless Configuration, but it's easy to find in the Ralink software utility.

Do a thorough scan for malware.You might be infected with something that is eating up your bandwidth and CPU cycles.

As far as I can remember, nothing was changed before it slowed down
Haven't moved it any further from the router, at the moment the laptop's on my desk about 3 or 4m away from the router through a wall and ceiling
Power output at 100%
No malware on my system according to Spybot S&D, Adaware SE and Antivir

Check your channel settings for both the card and the router. If one of them is off channel you can still get a crossover connection, albeit a poor one.

Both the router and the card are set to the same channel (11)
They have been set to channel 11 since I got them and have worked fine up until now

Doesn't TKIP also require you to configure RADIUS?

Can't you use AES?

I use TKIP because when I configure it to use AES, it wouldn't connect at all
Never heard of RADIUS - what is it?

Another method of security, I'm not sure if TKIP and RADIUS are supposed to go together, but I worked with an Asus router that said I needed to configure RADIUS if I wanted to use TKIP..

I'm probably wrong, though.

Try using AES with a simple passphrase like 123456890abc.

It seems that my router only supports 128-bit WEP, 256-bit WEP, and WPA-PSK
It also doesn't support AES, the option to use TKIP isn't changeable, if that makes sense - it's displayed so you can see it but there's no way to change it

Alright.

How's the connection without encryption?

It's about the same
It seems to be an intermittent problem - sometimes the connection's fine, other times it's too slow to be of any use, sometimes I can't get a signal at all
Have uninstalled and reinstalled wireless adapter drivers - makes no difference at all
Have also tried laptop far away and right next to the router - this also made no difference

Perhaps the router or wireless card are faulty.

Have you tried replacing them?