Newbie question-- where to throw my frogskins next?


Hey folks, my first post--

So my new year resolution was to get into vinyl and these past 11 months I've been on an very enjoyable, and thanks to craigslist fairly affordable, audiophile neophyte journey.  I really barely know what I'm doing, but think I've lucked onto a pretty sweet vinyl setup;

AudioTechnica 120 turntable (with their standard cart)
Marantz sr7007 (using pre-outs for front speakers, but built in for surround speakers)
Moscode 300 ($150 craigslist score!)
Klipsch Forte I (replaced crossovers and tweeter diaphragms) 

So my question is, if I wanted to throw about $1000 at this system, where would I actually hear the biggest difference?  Better turntable?  Tube preamp?  Save my money as the difference would be negligible?  

I'd love to find a deal on a Mcintosh preamp, but the truth is I use the system for home theater and gaming and appreciate all the HDMI switching and surround sound the Marantz is giving me.  But I am also listening to vinyl every day now...  :-)

Thanks in advance for any advice!
128x128argonsteele
A system can only be as good as its weakest link.  And for vinyl playback, the weak link would be sending the analog signals through the Marantz AVR's preamp.  And I just don't mean its phono stage either but its preamp section.  Even in so called "pure direct mode", its an afterthought.  That phono input the AVR has is just a  convenience and not for true hi fi performance.

So I disagree about a new TT/cartridge - it would all be wasted going through the AVR.  Concentrate on the weak link and getting the AVR out of the analog signal chain.  Find a nice stereo preamp with or without a phono stage because you can always add an external one.  If the pre-amp has an HT bypass feature even better.  This will allow your AVR to be integrated into your stereo system.  If it doesn't, you can still integrate by determining the Unity Gain position on your stereo preamp.  Google HT Bypass and Unity Gain to learn more.

An analog source is best kept with analog electronics. 
excellent advice everyone.  Thank you so much.  I will pursue!  I realize this is the high end of high-fi forums and I'm at the low end, but I really appreciate the guidance.  :-) 
@argonsteele
You don't  say if your 120 is the PL120 or LP120-USB. Both have internal pre-amps, I believe. It is important not to use them; but to use the much better Marantz Phono section. If you read the following you will see how some other people describe your turntable, how it can be tweaked if you know someone capable, and how it's biggest drawback seems to be that it is not a good match for the AT-95 or any cartridge that tracks at over 1.7 grams. So a cartridge upgrade is a good place to start to give your turntable a fair chance. Best of luck and have fun!
http://www.vinylengine.com/turntable_reviews.php?make=Audio%20Technica&model=AT-LP120-USB
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.