Next upgrade for vinyl rookie

How big of difference would swapping out tables be compared to a OL arm upgrade?

Do you not know that the stock 250 is already better than the P2? Sell the arm with the table (b/c it won't sell without it), and maybe keep your accessories depending on what you choose as your next table. I don't think the LP12 is a good choice for a rookie, maybe a used P25.

I think that you have a really nice rig going there. The table and cartridge is quite fine. If not a record cleaning machine, as described above, I would suggest a new phono preamp, perhaps a black cube or Monolithic. I base this suggestion on the experience that solid state distortions from electronics, particularly phono stages and preamps, are far more irritating to me than the inherent distortions in transducers. I have spent some time with the Project phono stage and it is not letting through all of the analog glory of your front end.

Doing some Tweeks like some mentioned above are a good idea before dishing out more money. Do you have a proper alignment tool? If not, getting the cartridge aligned is the first stop before passing judgement on your current setup.

What is it that makes you unhappy with your system? What are you expecting out of your system? Are you sure that your source of dissatisfaction is your table?

Personlly, I would buy the DiscDoc cleaning system, then spend the rest on some vinyl.

As others have mentioned, you've got a good arm and cart, but a not so good table and phono pre. 400$ won't get you far w/ the table, but it will w/ the pre. I'll second TWL's suggestion concerning the end stub, Sugarbrie's tip on alignment, and Nrenter's vote for the DiscDoctor stuff. If you still feel like spending some money, I'd get the Monolithic phono pre. They can be found here on audiogon for >300$ (and check out the tubed phone pre kit at bottlehead.com--interesting). You can take the arm and phono pre w/ you when you have enough for a significantly better table. Have fun.