It's actually running Ok now, but I bet it won't last long...
It sounds like your connection slows down whenever your sis uses Limewire. When you notice a dip in your connection, check and see if she's downloading anything.
The signal strength is only two bars, but it's been that before and I've been getting 2MB/s
Then theres no other way. Danny, your comp is infected with "WiFiLagidousis Type 1"
Omar, how can I remove it?
Unfortunately there is no cure. But there is a treatment.
Buy a PCI wireless card, they are usually faster than USB and I would think that more stable as well. May cost more, but it'd be worth the try.