Arch Linux should run on any x86_64-compatible machine with a minimum of 512 MiB RAM, though more memory is needed to boot the live system for installation. [1] A basic installation should take less than 2 GiB of disk space.

How much RAM does Arch Linux use?

Arch runs on x86_64, minimum requires 512 MiB RAM. With all base, base-devel and some other basics, you should be at 10GB Disk Space.

How much space should I give Linux?

The base install of Linux requires about 4 GB of space. In reality, you should allocate at least 20 GB of space for the Linux installation. There is not a specified percentage, per se; it is really up to the end user as to how much to rob from their Windows partition for the Linux install.