Recommendations for a TEK 465b probe

Any x10 probe will do, have a look on ebay. The real question is does your 465 meet the bill. If your doing program developement, sometime soon you will need more that 2 channels and storage of some sort.

Some tips:

When trying to figure out whether a waveform makes sense, you are going to want to trigger right before the waveform begins. Reserve a port pin as your 'trigger' pin, and wiggle it right before the event you want to monitor in your main loop. Then, view the waveform using the other channel.

I have a 475. There are special probes that you can get, which will do the 10x multiplication just by plugging the probe in. (I have a P6106A, that I got on EBAY.) Other probes (from probemaster!) have a switch that you can use to switch between 1x and 10x.

For PIC work, a 20MHz probe is probably all that you need. They are also fairly cheap, and you need two if you are going to do the trigger trick above.

Remember that the ground of the oscilloscope is not floating. So, don't try to connect the ground up to anything that is not isolated, or you'll end up passing too much current through the probe, and could even create a dangerous situation. You can get isolation transformers if you really need to do this (for example, if you are working on a non-isolated power supply or something like that). You can also float the scope itself by disabling the third prong, but that is NOT recommended, for various obvious reasons.

Have fun. A scope makes it possible to visualize all of this cool stuff. As a software guy, I spent far too much of my career thinking hardware was just funny data structures... I'm having way more fun these days.