Old Airport Express vs New Time Capsule

[trey851]

I was wondering if some one could help me out. I own and old airport express (from 2005/6 maybe),and it is my only wireless router, which I use mainly for wireless music and I am thinking of buying time capsule to back up my laptop. If both of these are running on the same network will the entire network run at the slower speed of my airport express or will the network run at the faster speed that time capsule uses(with the obvious exception of running at a slower speed when streaming the music threw the airport express).