http://www.sonigen.com/
I've recently discovered a most useful and engaging ''virtual modular'' software synthesizer, for free!
Sonigen let's the user add modules and design patching between these modules to create sound and process audio routed thru the system.
I've restored an Acer notebook which i bought in 2009, so it can be the host for my copy of Sonigen.
Since Sonigen is a ''stand alone'' application there is no need for a host DAW like protools, logic or cubase.
With a USB/audio midi interface connected to the notebook, Sonigen becomes a connected part of my midi synthesizer system....basically it's a new piece of hardware.
In the past I have restored older computers just to run one or two synthesizer and/or sound production applications...My old iMac G3 is still functional to this day...with less than 6 applications installed it is a useful device within the home studio. Today it is a digital multiTracker, specifically Logic Audio.
I highly recommend ''SoniGen" for any synth-lovin freak....it's also available in vst-i format so you can run it within your favorite DAW.