Yeah...I like Linksys. But Netgear, and DLink are also good consumer manu's.
Wireless B (802.11b) has a max throughput of 11mbps (megabits per sec.) in theory. In practice, you may get 8.
Wireless G (802.11g) has a max throughbput of 54mbps, with a more realistic expectation of 45ish.
Obviously you're throughput is dependent on a BUNCH of variables (do you have a microwave? lol).
Anyway...my point is that G is faster, and if you have the money...go for it. But B is perfectly fine for most applications.
You could prolly get some B for pretty cheap on eBay, etc. To buy anything new...try CompUSA. They've always got real good deals on SOHO net equipment (if you don't mind waiting 6 1/2 years for rebates. <g>).
And...yeah, you need (well, technically you don't NEED...but it's the very best way to go) a wireless router. I recommend just picking a technology (B or G) and then a brand (Linksys, Netgear, etc.) and then buying all matching equip. You'll need PCI wireless NIC's for each desktop/tower, and a PCMCIA or USB wireless NIC for the laptop. USB nic's would work on the desktop/towers too.
Lastly, I strongly suggest that the stationary computers be connected with copper. It's more reliable, faster (100mbps), and...well, that covers it. Cat5 is fine, Cat5e is a tad better (and necessary if you want to take advantage of gigabit technologies).
If this is absolutely no help, I can go shopping and post some links to actual products (SKU's).