High latency issues

Hi, I have a beetel 220bx modem and a Linksys wrt54g wireless router. I use the wireless feature to access the internet from my laptop. Over the past few days I've noticed that my latency is rather erratic and its often going up to 500ms on cs and even when I've run a ping command to other websites I notice that the latency is quite high (500-600ms) to google. However, if I try to ping my router the latency is normal (2ms) and doesnt fluctuate.Is anyone else having this issue? Any suggestions would be welcome..I'm trying to figure out whether its an airtel issue or a problem with my equipment.

High latency is related with bandwidth and number of users from t3 to t1. latency would be 50ms to 250ms. If bandwidth drops below 512k, latency would be 500ms. If it drops below further 256k latency is definitely higher due to sharing connections. Any school kid can calculate that in this situation wireless connection is under scanner/shared.