hardware TPM module - install?

[Wolfgang S. Rupprecht]

What is the current feeling on installing an optional hardware TPM
module on a motherboard that has a header for it?  My most recent Asus
motherboard has a header for a $20 TPM module.  From what I understand
this module has a hardware random number generator that can spit out
10's of kbits/sec of entropy and has several different modes for storing
user-loadable crypto keys.  On the surface, both of these sound like
useful things.  Is there a downside?  Can a flawed RNG pollute the
entropy pool in a way that lowers the security?

-wolfgang