Right and wrong.
For DRVSM, TCAS and/or TCAS II is not required. In other parts of the world I believe it is. With that said:
No such thing as TCAS with Change 7. TCAS (or TCAS I) is signifigantly different from TCAS II, which does have a Change 7 software revision, required for RVSM if TCAS II is installed on said aircraft.
With a TCAS I setup (Note TCAS I, not TCAS II) it can only be used for TAs, due to design limitations. It will be more of an annoyance in RVSM, because it will point out traffic 1000Ft above/below you.
If you have a TCAS II setup, it MUST be configured with the Change 7 software. Software prior to the Change 7 update is set for interrogating XPNDRS at 1500 feet, not 1000 feet, so you would be getting TAs and getting as well as sending RAs all day long in RVSM airspace, and since you can deviate from an ATC clearance (Only TAWS has a higher priority) when following a RA, it would cause lots of trouble.
A little background:
With TCAS II, the RAs (Resolution Advisories) are cordinated between the 2 aircraft before order is given. For example, if aircraft A and aircraft B are about to collide, the TCAS II boxes talk to each other so the pilot of Aircraft A, for example, is told to Climb, while the pilot of Aircraft B is told to Descend. In the earlier copies of TCAS II, the boxes would not talk to each other; they would just tell the pilot to do what is prudent for the situation, possible climbing or descending the aircraft right into each other. Another key part of TCAS II is precautionary RAs such as "Do Not Descend" or "Monitor Vertical Speed".
If you get bored and have some free time:
http://www.arinc.com/downloads/tcas/tcas.pdf