Suggested buildFollow

for your own surviveability:

http://www.wowhead.com/?talent=IAMrVRfkVtboMxZxx0z

for better raiddps:

http://www.wowhead.com/?talent=IAMrmRfkVtcoMxZxx0z

for better dps/raiddps:

http://www.wowhead.com/?talent=IAMrmRfkVtcoZxx0tM

if you care to link your armory i might be able to tell you more.

Oaken gave you some great builds.

The third would definately benefit a lock in a 25 man with a Shadow Priest and other locks.

I do feel for a lock just starting that the second build is going to be your best bet. With 3/3 in Malediction you give the raid much more support. If there is a shadow priest he will benefit from this build as well.

There is also a 0/21/40 Build that I use that is also very high on the damage meters. This build is very dependant on gear. I currently only have 17% crit chance unbuffed and am still beating my old UA spec. If you want to look into this spec remember that healers will have to keep and eye on your lock because he will be lifetapping a lot. I always make sure my healers are aware of it and I tell them to tell me not to tap if they cant handle it.

Let me know if you want to see this build.