However, unless you'll be running tons of CAT5 cable, it's going to be a bit cheaper to go with a wired connection, simply because the cards are cheaper. Realtek isn't necessarily the best, but they have more than acceptable performance for home use and are extremely cheap. Sure, you can get something better from 3COM or Intel, but they will cost more.
As previously noted, this will not have any effect on your download/upload speeds as these are determined by your ISP. Unless you have a T3 line coming into the house, a 10Mbps connection is more than enough, however, transferring around data in your network would be...well, slow.