Thoughts to consider when looking at improving your setup.
Is your computer past it's prime? Do you not know what to do? When it comes to computer upgrades, there are many options available: do you move from a desktop to a laptop, or vice versa? Do you buy the best-performing machine, or just the bare bones which suits your requirements? Do you go with a completely new machine, or a second hand machine? Or do you just upgrade what you have?
I'm here to answer all your questions. Since each case is different, you should give me a call to discuss your particular situation, but here's a general outline. If your computer is going to be in one place all the time, get a desktop machine. It will last longer, be faster and easier/cheaper to fix. Unless you're doing super-heavy CAD, graphics, audio/video work or gaming, go for the bare bones - even the cheapest machine nowadays more-than fulfills most users's requirements.
If you're a "heavy user" as above, you want a middle-tier machine - the advantages you get from the bleeding edge are insubstantial compared to the performance gains you'll get from saving the money and upgrading in a years time. If you're looking at second-hand components or computers, if you're a heavy user you can get away with using 2nd-hand cases and power supplies, but get new middle-tier components for the rest of it. If you're a typical user, typically anything built within the past 5 years will be fine for you.
As for upgrading your existing computer, if your computer is quite old and still has a HDD (hard disk drive), it will do much better with a new solid state hard drive (SSD). Cloning from your old hard drive to a new one is a simple and painless process which I can help you with. And if you choose to buy a new computer, I can make sure the transfer of your data and programs from your old one goes smoothly. Get in touch with your personal needs, and we'll figure out something which suits you.