I need a wireless adapter that gets good FTP speeds from about 50 FT

[leglez]

I am installing an xbox in my car to store my music and movies so that I don't have to pay for an overpriced Ipod or similar

I am wanting a wireless adapter that I can hook up to it so that all I have to do to put new music on is pull up next to my house and FTP them over and my computer is about 50 FT from my car

So is there any wireless adapter that works great at 50FT?

Also the adapter has to be ethernet

Should I get a better antenna?

Also I have a WRT54G Wireless Router will this give a good connection for 50FT? If not can I upgrade the antennas

How is this?
Adapter
Antenna