Storage Spaces? Built into Windows, easy to set up, requires no extra software. Choice of simple (what you want, essentially software RAID 0), mirror (same on both drives, essentially RAID 1), and parity (needs three drives, combines them for a mix of performance and data security, essentially RAID 5).
Note that simple storage spaces (and any other "striped" drive combination pairing) has a slightly higher risk of data loss - if one drive fails, you'll lose all your data, not half of it.