To run RO, you don't need much. I would recommend using an AMD processor for a budget-performance build with a Radeon video card.
You want a recommendation on the processor, motherboard and ram.
Processor: AMD Phenom II X4 965
- Run you around $99.99 and is fantastic for gaming. Beats the AMD FX 8150 when overclocked.
Motherboard: Several of them..
1. ASRock 970 EXTREME3 AM3+ ($99 and is loaded with great features)
2. GIGABYTE GA-970A-D3 AM3+ AMD 97 ($99)
RAM:
If its RO and Windows XP, you really don't need more than 2 GB of RAM. However, RAM is cheap and you can get 4 GB for like $25-$30.
E.g) G.SKILL Ripjaws Series 4GB Clocked @ 1600 MHz DDR3 will run around $26.99 (US tho)
Video Card:
RO really has low requirements for graphics but I wouid go with a nice cheap & cost efficient card. Something like a Radeon 6670 would do just fine and costs around $70.
http://www.newegg.co...N82E16814102988 (Sapphire)
http://www.newegg.co...N82E16814125403 (Gigabyte)
http://www.newegg.co...N82E16814127666 (MSI)
So with everything, you're looking at a $400 to $500 build once you accompany the case, power supply, & hard drive as well. This build will allow you to play more graphic intensive games as well but keep in mind, you get what you pay for.