we rent a townhouse that was foreclosed on by hoa. the new owner wants us to sign a new lease. we have a valid lease with 24 months left.

This area of the law is very up in the air.  While Federal and State authorities have been quick to clarify the protections of tenants in lender foreclosures, HOA foreclosures have not been made as clear.  The Nevada Supreme Court has recently stated in an unpublished opinion regarding HOA foreclosures that the Purchaser has all of the rights (and retains all of the obligations) of the previous landlord under the Lease Agreement.  Under Federal law, in most cases, the new owner after foreclosure cannot evict the Tenant until the end of the lease with two exceptions (1) the new owner wants to use the home as Buyer's primary residence (in which case Buyer only has to give Tenant a 90-day notice to leave) or (2) Tenant does not pay rent or violates the lease.  Unfortunately an argument has been made that these protections only apply to lender foreclosures and may not extend to the foreclosure of HOA or other lien interests.