Hi again Alex - as to a new router, depends on what's available in your locale and what you want to invest - in the spring we switched from PCs (after nearly 30 yrs!) to Apple (MacBook Pro & iMac) - I could not get the iMac to work well w/ my Cisco Valet 802.11n router, so purchased an Apple AirPort Extreme which was about $180 - of course, you can pick up nice routers for half that price. I would suggest searching online for recently reviewed routers,e.g. checkout the PC Magazine & PC World websites (such as HERE) - make sure the reviews are from this year for the latest brands & models; also, google 'best 802.11n wireless routers for a bunch of hits. Now, there is a newer protocol (802.11ac) but IEEE's final approval likely will not be until this fall or later?
As to setup, I'm assuming that you have a broadband modem (cable or DSL) - I have my cable modem going into the WAN port of the AirPort Extreme and then an ethernet cable from one of the LAN ports into my iMac; each router brand will have fairly simple instructions for a 'basic' setup (all that you likely need) - some have 'easy' setup buttons and/or browser configuration programs (like your Linksys 54G); for my Apple router, there is an app called AirPort Utility instead of a browser option; so you'll just have to see what the brand name directions will be - the reviews might also give you a clue as to ease of setup? You will also need to setup wireless security (WPA2 is what I am using). Good luck and I hope you get a stronger signal! Dave