Oracle EBS R12.1.3 Upgrade Hardware & Software Requirement

Currently we are on 11.5.9 and we want to move to Oracle R12.1.3 (most probably Upgrade)

Size of Organization: 

The client is small, based in US and around 20 users. 11 OUs, 1 Ledger. No Multicurrency, No Intercompany. The client has the Peoplesoft at Higher level. There are lot of interfaces from Oracle EBS 11.5.9 to other Subsystems. Client is only using Receivables and General Ledger. It is a small implementation.

Current Hardware:

Hardware: HP ProLiant DL380 G3 Dual Intel(R) Xeon(TM) CPU 2.80GHz

OS: Red Hat Linux Advanced Server release 2.1AS

Memory: 4GB

Swap: 2GB

Total disk space: 400 GB

 Current EBS Software:

Oracle EBS 11.5.9, however the Financials part of it is 11.5.10. Yes we have existing license and