Wireless signal booster vs new router

[michaelt196]

I recently moved and am currently getting 18% wireless signal (based on ralink program) or 1-2 bars based on windows vista's network icon. I have tried two different wireless adapters and received similar results with both. I noticed that even a foot of movement can increase download speeds from 4mbps to 5mbps. I am a comcast subscriber with a linksys BEFCMU10 v4 modem and linksys wrk54g router. Is this router's speed affected by an out of date DOCSIS version? Will getting a new router dramatically increase range/speed? Or will a wireless signal booster simply get the job done? I'm not looking for just speed but mostly stability, mainly in a multiplayer gaming environment. I'm also keeping cost in mind as I know that getting a signal booster would prove cheaper than a new router.