Oscilloscope Advice? (Best way to check a circuits frequency response?)

[iandy4]

Hi Guys,

I've been building various opamp based circuits for a few years now and it's getting to the point were I'd like to be able to see how stable my power supplies are and how different components are effecting the audio signal and its frequency response.  In the near future I'd like to get into doing my own amp repairs as well.  Does anyone have any advice about what to look for in terms of oscilloscopes and tone generators?

Can I use an oscilloscope to check the frequency response of pickups? 

What I'd like the most is to be able to see the whole frequency response of the circuits I build or of guitar pickups for that matter.  Is an oscilloscope the right tool for this?  I imagine I'd need a signal generator that can output a tone at all the frequencies from 20Hz to 20kHz (the ones I'm interested in) and use the oscilloscope to find out how the circuit in question effects the various frequencies.  Is there a tool that could show a graph of the frequency response right away or would I need to plot the results myself at the various frequencies to make my own graph?  Can digital oscilloscope do this? I've never used an oscilloscope before but I've been doing some research and it looks like the Rigol DS1052E might be a good one for me.  It costs 380ish dollars.  I also see a lot of old analog ones on ebay for around 100 incl. shipping.  Any advice would be greatly appreciated!

[Hides-His-Eyes]

A white noise generator and an oscilloscope with an FFT function should do it.

[CynicalMan]

I use a laptop with a VSTi white noise generator and this:
http://www.voxengo.com/product/span/