Spend the money and get a nice Linksys N. Regardless of which your laptop uses, both N and G adapters can connect to the N router. Almost all N routers can broadcast in the 2.4Ghz and 5Ghz frequency ranges and some of the nicer ones can use both ranges simultaneously.
I use a 120N and it’s ok but I wouldn’t recommend it. My dad has the 310N and it’s great but they discontinued the model after screwing up the later revisions :\
For best performance, you’ll want a simultaneous dualband, this gives the raw range of the 5Ghz frequency and the obstacle penetration of the 2.4Ghz frequency. I would recommend the WRT400N or E3000. The E3000 is pricey but you want something that’ll last and this is an area where you definately get what you pay for. Both support DD-WRT.
Unfortunately right now there’s really not a good middleground in terms of price. The WRT610N is a perfect balance of features and price but has a severe overheating problem. The E1000 is 100Mbit and only has a 2×2 antenna config with 2 antennas, making it pretty much worthless in terms of useful wireless. The E2000 has gigabit wired but isn’t simultaneous dualband and only has 3 antennas. Better but not great compared to the E3000’s 6 antennas 