like Cornbread said, accounting is a totally different animal, although it can be a good springboard if that's what your college training was. Sounds like we can knock that one out.
Generally the finance heirarchy goes like this: analyst/associate/VP/director, though there is some variation and nuance within those, but for my purposes here we'll just go with this structure.
first thing to think about is if you want to be buy-side or sell-side. generally speaking sell-side is better pay, worse hours/lifestyle.
in investment banking (IB), unless you go to a small shop and can hit the ground running, you won't be able to break in at the analyst level. Your likely entry point is at the associate level, which you either need an MBA for or have to have been a good enough analyst to get hired directly into that position without going to Bschool. IB is sell-side.
Being a securities analyst can mean a ton of things. It can be buy-side or sell-side. Equity or fixed income. Institutional or retail(individual investors). The fixed income universe is far bigger than equity. Equity tends to be a more tangible concept for those not in the industry b/c you can associate a name and a product with a stock. Fixed income can mean fixed rate or floating rate debt, investment-grade corporate bonds (dying product, don't go into it), high yield bonds, leveraged loans (my area), govt bonds, asset-backed securities (ABS), mortgage-backed securities (MBS), convertibles, and all sorts of other stuff including derivative products (myriad swaps, options, swaptions, futures, etc.). I wouldn't expect you to know which area you like best, but you have a lot to choose from.
Being a portfolio manager can also mean a bunch of different things. PMs are VP level or higher. It can be for retail or institutional investors, it can be a mutual fund, structured products (my area) like CLOs and CBOs, hedge funds, insurance companies, banks, endowments, etc etc.
Being a financial advisor for retail investors tough, but if you can build a good book of business you can do well. This was always the least attractive area for me, but there are certain personalities that thrive best in this area.
If you don't want to start your MBA right now, get cracking on the CFA (http://www.cfainstitute.org
). Simply indicating your candidacy for the CFA on your resume will help get you in the door at a finance job, even if it is in the operations or IT areas. Passing the first level or two will take you a considerable step further. http://www.vault.com
is also an excellent resource for ground-level info.
feel free to ask me anything you want.