Cartridge or cable upgrade

I would do both really. Which one is your choice. I use the Dynavector 10x5 on my Rega and it is awesome! I have never been a fan of Monster Cable (multi stranded) Signal cable makes a silver series for a lot less money than Anti Cable and you will be amazed at the results. Or you could look at something from Morrow Audio (around $150). Nice system tho the upgrades your thinking of will really bring home the dynamics and resolution. Enjoy!

Get a new 10x5 and buy a good used pair of IC's like an AQ Jaguar for 100-150. They sound way better than anti cables and have the DBS system which is a good choice for TT's because they stay broken in with little use.

Again, agreed with both Mattmiller and Zd542,
There are many cables out there better than the antis at a more affordable price.

You all rock. Thank you for all the advice and guidance. Some further questions:

1. How thick a mat should I get if I go the Herbie Mat route?

2. Yes, the table is probably the weaker link in the system, but at this stage I'm not sure how invested I want to get in the analog side of things. However, if I do pursue it, what's a good table that would be a step up from the 5.1? Figure ~$1000 used.

"Yes, the table is probably the weaker link in the system, but at this stage I'm not sure how invested I want to get in the analog side of things."

Your TT is more than adequate to get you started in vinyl. You'll see that upgrading is very different for digital and analog. With digital, you upgrade to something better sounding, but after that, you feel the need to upgrade again. And again after that. With vinyl, you can think of upgrades and improvements, but are not so compelled to do them like digital. Its much easier to enjoy what you currently have, even though there are improvements to be had.