@lukiszlak No, more RAM wouldn't help much with streaming. Faster CPU and graphics card would benefit you the most for Streaming and gaming at the same time.
To get good peformance for the stream and your game, you would have to buy new CPU and Graphics card. It's not worth it to upgrade your current rig, since it's old now and doesn't provide an upgrade path to the newer CPUs.
If I'm not mistaken, AMD Athlon II CPUs are AM3 socket, and new AMD CPUs are usually AM3+ socket. Some Motherboards support AM3+ by a simple BIOS update, and some are not, so you need to check that.
If it supports, and you want to stick to AMD, you can aim for some AM3+ CPU, 6 or 8 Core models are not bad for heavy streaming. If you decide to do an upgrade, let us know so we can suggest something. Same with your graphics card.
For OS, It's better to use Windows 7 64bit. It's a newer system and provides some features that XP doesn't. For example, Xsplit can capture all PC audio directly without any other software/hardware, so it's much easier to set up.
Edit: I just realized this is not a Tutorial. Moved to Technical Support.
Comments
When you say always you mean ALWAYS even without xsplit running?