Re: internet explorer
Definitely use firefox. I've been using it for a few years now and it's great. I don't even touch IE anymore!
Also get Gmail, it's great. I've been using them for a long time and they now offer over 6GB of storage for free and have other neat features such as an online word processor and spreadsheet program. If you want to access your email from your desktop, get thunderbird. I recommend thunderbird because outlook is expensive and not worth going out to buy unless you already have office.
Desktop: Dell Dimension E510, 2.5GB RAM, Intel P4 3.0GHZ, 250GB HDD, Windows Vista Premium. Might not be the best, but the old girl is still running good.