Keep the E2160. Add 4GB RAM and an SSD. Install Linux Mint. It will handle Google Docs, LibreOffice, and email perfectly. Upgrade cost: $20 (SSD only).
An upgrade makes sense only if:
: A legendary budget quad-core chip. It is widely compatible and very affordable on the used market. Intel Core 2 Duo E8400 / E8600 intel pentium dual cpu e2160 upgrade