The idea of the Time Capsule is that it's a one stop shop for backing up your Leopard Mac.
As usual the TC looks great and un-boxes beautifully, no ethernet cable in the box, though which seems a bit mean. You get the white box, the power supply and the disk and manuals.
So, I tried to set-up the TC wirelessly as part of my network but I didn't get anywhere with this approach. I kept getting error messages and had to give up, so then I connected the box directly to my ISP supplied router (you need this if you get your internet through the phone line) via ethernet. This worked beautifully and then I did a wireless backup - unfortunately this was very slow - 48 hours for 120GB hard drive. So I recommend using the wired option if you can.
Since then I've had an 'n' network router and an easy wireless backup so I'm very happy. Setup is a bit painful and it would be great if Apple would add an ADSL modem to this, then it would be a one box solution.
NB Note this box runs VERY hot and there are lots of reports of it giving out at the 18 month mark (safely out of warranty). Lift it up or use a laptop cooler - also it is covered by Applecare on any of your macs