Newbie question-- where to throw my frogskins next?

You need a good pre-amp to be honest. A Tube based Pre-Amp and a Decent Phono Stage to start off with.

By the way we all started just like you. Nothing to be ashamed off. You can pick up a very nice Tube preamp on audiogon within your range.

Yes my turntable is the USB model with the At-95 cart and I am using the phono stage in the Marantz.   Yesterday I spent and hour reading about removing the phono stage from the turntable, but I think I'll hold off on that adventure for now.  More than anything this thread is confirming that I was at least already pointed in the right direction.  I think I'll continue to pursue all three paths at the same time; some small affordable up-grades now, like cart and maybe phono preamp, while looking for the right deals on a better turntable and tube pre-amp.  Both those larger ticket items are intimidating because there are so many more obscure choices out there at the mid to high end.  Guess it's more hours on the internet for me.  (I spend some time learning about the Linn axis this morning, which I'd never heard of, but I'm a little afraid of that eBay one as it seems to need a new power supply already).  Deep in my heart I want a Mcintosh tube pre.  

One follow up question.  Do others agree that the Moon phono preamp suggested by 2channel8 is a good choice?  That seems like a sweet price I could take the plunge on today, but I also know there are many options in that arena.   :-)

Ah, my poor friend. You are obviously one of us helpless addicts now. What a sweet addiction. Don't spend so much time on the net that you neglect the listening.  :^)

:-)  OK, I pulled some triggers.  Ordered the moon phono amp after reading a few reviews, the AT 120 EB cart, and a cork mat for my turntable.  That's my budget for this week.  I'll continue to troll craigslist for the bigger items.  Thanks everyone!