Welcome to the community, Charan!
It's going to be really helpful to share what you plan to do with the extra storage. As @Jp2slow mentioned you can easily add to that HDD if you have the extra space. If you intend to use the 2/3TB HDD as a secondary storage drive, then I'd suggest you check the upgraded mainstream PC products in the
WD Blue Family. The larger than 1 TB capacities are in the 5,400 RPM class and are a reliable secondary storage solution for your massive data.
If you, however, look for something high-end and performance-tuned, then I'd recommend you check the
WD Black . This model offers various massive capacities and is in the 7,200 RPM class with 64 MB cache. Another advantage of this hard drive is its 5-year limited warranty which definitely gives some peace of mind.
Either way, always backup your data and have, at least, two copies of your files stored in different locations/drives (on-site as well as off-site). This is the best way to avoid any potential data loss.
Keep us posted if you have more questions!

SuperSoph_WD