Diversification?

This isn't my first blog, nor will it be my last likely, but after randomly falling into the online investment blogging community, I decided it's a good idea to start tracking my finances and the like via the Internet... anonymously, of course.

So here's a little bit of info about me to get started: I'm a young professional in her early 20's. I've been out of undergrad for two years now. My income is $35k a year, benefits included, except sans a 401k. Chance of raise/promotion within next year: 15%. Chance of company going out of business: 55%.

I'm fortunate in the sense that I have a decent amount of savings and no college loans. Savings from both my dad putting aside some funds for me for the awkward post-college year, and then extra cash from a lawsuit over a broken arm when I was little. My networth right now is around $27k. So I realize I'm better off than many other people my age, despite the fact that they might be making $50k a year and I'm only at $35k. Or at least our actual income after bills and other expenses is usually about the same.

Since this is an anonymous blog, I feel ok talking about the details of my finances. I haven't talked about it much on my main blog since it feels weird letting people know about how much I'm worth, or not worth. But finances are one of the things that I really need to talk somewhat publicly about, since I'm unsure of how to handle my money, with the exception of spending it. I'm very good at spending it.

So I recently opened a few random mutual fund/IRA/CD accounts, as I'm attempting to "diversify" my portfolio. I know I'm supposed to be living under my means, but I often fail to do that and spend more per month than I take in. Obviously that's a bad idea. But i'm hoping that at the least, putting some of my funds in high-interest accounts will balance out my poor spending habits.

Ok, so here's the breakdown of my accounts right now... (I'm going to try to keep tabs of this, as well as my budget, on here)

$2,143.54 - Checking
$7,421.99 - CD - 3.1 % Interest, matures 8/28/08
$5,510.58 - Maximizer Checking
$1000.63 - Savings
$5,000 - 8-month 5.01% Interest CD
$3,000 - Vanguard Mid-Cap Growth Index Mutual Fund
$3,000 - Roth IRA, in 2050 Retirement Plan fund

Well, the last three of these items haven't officially been started yet. I signed up for them yesterday. I'm waiting for all of the electronic transfers to go through. I realize investing in a Mid-Cap Growth Index Mutual Fund. Afterall, the smart thing to do is to invest in large caps, right? But I figure if I put $3000 into a mid cap fund, I can also invest in a large cap fund if/when I ever get a raise. I'm $1000 to maxing out my Roth IRA fund.

I don't understand the Roth versus regular IRA option, being as I know the Roth is all after-tax income and the regular IRA is pre-tax income then invested. But what should I be investing in now? I'm only making $35k a year, so it seems like I'll most likely be in a higher tax bracket when I want to retire. Afterall, I plan on making more than $35k per year when I'm 55 or 65 or whatever age it is I can retire.

And if I sign up for a Roth IRA now, can I move to a regular IRA at any time? Or am I stuck in the Roth?

Finally, how about my mutual funds - how much will it cost to change them from mid-cap to large-cap if suddenly I realize I ought to be a bit less risky in my investing? Gosh, I'm so confused.