I agree with Dejans' answer:
Try one of the many Lightweight Linux distribution, see list below:
Make sure, that your hardware requirements are met, before deciding on one of the distros. I also suggest you to definitely buy "1GB of RAM" or maybe "2x1GB of RAM" on ebay for a small amount of money, so you can't go wrong with Lightweight Linux and also it is a huge improvement in your work flow!!
For your current 512MB RAM option, please see: List of Linux distributions that run from RAM - which shows you the required RAM specs.
Also antiX (see link below) seems to be a good/fair option for old/older computers, to be considered!
Alpine Linux -
A security-oriented, lightweight Linux distribution based on uClibc and BusyBox. Mini download is 66 MB; base system (excluding kernel) is under 5 MB.
Lightweight version of its parent distribution MEPIS Linux, based on Debian testing. Core Install: 128 MB, Base approx 300 MB. Package Manager: Synaptic
A very lightweight distribution capable of running on an Intel 386 and 3 MB of RAM
Bodhi Linux -
A lightweight and minimalistic distribution, based on Ubuntu 12.04
CrunchBang Linux -
A relatively large (771 MB) Debian based distribution designed primarily for speed and ease of use.
Damn Small Linux -
Download 50 MB. Additional software available as "DSL Extensions" and using the Debian APT tool, which has to be installed. "Light enough to power a 486DX with 16 MB of RAM"
Feather Linux -
Lightweight Linux Distribution derived from Knoppix. Now dormant.
Lightweight in comparison to Ubuntu, it uses the LXDE desktop.
14 MB distribution based on Tiny Core Linux.
Peppermint Linux OS -
Peppermint Linux OS based on Lubuntu
It weighs in at under 300 MB, making it a lightweight contender, comes with the LXDE and KDE desktops
Puppy Linux -
Lightweight relative to most other Linux distributions Download: 133MB. Package Manager: Synaptic (Lucid Puppy Ubuntu Compatible version)
Semplice Linux -
lightweight, fast and simple, based on Debian Sid
35 MB distribution; Package Manager is Tazpkg with its repository of packages
Tiny Core Linux -
12 MB distribution; Software repository: TCZ packages
Trisquel Mini -
Lightweight version of Trisquel with LXDE