Is it possible to change my Apple ID, what I use to log into iTunes to my already existing @me account? I'm unable to do it so am wondering if there is a workaround?

I suspect the answer is no, so my follow up question is can I transfer over all my purchased content from one account to the other?

I actually found a similar thread that's recent but it did not mention anything about transferring your content from the old ID to your new @me ID. I think I'm either going to have to start fresh with the @me or leave things as they are with my gmail ID for iTunes. I'm pretty sure I'm SOL, just thought I would dbl check.

No, and unfortunately No.

Yeah kind of what I suspected. Thanks.

It seems as though you can How to change the name you use for your Apple ID (http://support.apple.com/kb/HE40)

I don't think it would work for an existing Me.com account.

There's the disclaimer: Some Apple IDs, like those ending in @mac.com or @me.com, can't be changed.

Although there's a discussion from 2009 that suggests you might be able to get around it.
https://discussions.apple.com/message/10530266?messageID=10530266#10530266

While you can normally rename an Apple ID to another e-mail address, you can't use an e-mail address that's already been assigned to another Apple ID. The problem with @me.com accounts is that they are already Apple IDs by default, and Apple cannot merge Apple IDs at this time.

The idea mentioned in the Apple discussion thread suggests that previously purchased content could be re-downloaded under a single Apple ID, however I do not believe this is realistic. While Apple could theoretically transfer your purchased content from one Apple ID to another simply by "giving" you the same content under the new account (basically allowing you to "repurchase" it at no charge), this is not something that Apple support is willing to do, nor likely even setup for (in the sense of being able to automatically mirror purchase history between accounts -- it would likely require somebody in support to go through your purchase history manually.

The good news, however, is that at the end of the day it doesn't really matter if your accounts are separate. You can continue to use your existing iTunes Store Apple ID for purchasing and re-downloading content and use your @me.com Apple ID for iCloud on the same device with no issues whatsoever. Basically, the accounts used in the various sections of iOS are unrelated to each other and do not have to be the same (this also includes iMessage, FaceTime and Game Center accounts, which can also be separate from your iCloud account and iTunes Store account).