Right now a refurb computer is probably a bad idea, as platforms changed dramatically in the last year with the advent of Vista. A refurbished computer will probably have an older board supporting older sims and less memory, ide drives. While it may be Vista compatible, it won't allow you to upgrade the way you need to as more applications demand more resources.
Also, a refurbished computer (unless it's a recent factory model which was sent back and repaired, in which case ignore the rest here.) will usually use an older mother board, which is what will blow first. You don't know the age of the power supply, which is what will blow second, and your components - start with the video card - may be behind the times.
I assume you want a desktop and not a laptop. You haven't said what you are willing to pay or what you need, but I just purchased an ACER with 2gb ram, Vista Home Premiium, 140 gb SATA drive for something like $390, and I have seen similar offers.
I am not sold on Acer, especially their service, but with what I paid I can slap in a new motherboard and a new OS (or my old OS) and be happily on my way for still a deal. I have heard very good reports on Dell. Less so on HP, but every brand has their successes and their lemons.
You can find very good Dell offers with a little Googling. If you buy one, however, buy it as offered, since their a little better here and a little better there strategy will get very pricey very quickly.
There are price comparison sites all over the net. Comp USA is also slashing prices as it closes, so it might be a good time to pick up a deal there. You won't be able to take it back, but you will have the standard manufacturer's year warranty, so you have little to worry about.
Your older printers and scanners may or may not be accepted by the new computer. This is not a question of brand, since all PC models come down to Windows in the end, but the Operating System (Windows) version. Vista, for instance, will not accept some older printers (old being over three years). There are no drivers available for them. If you get a model with XP (if you felt the need, you could upgrade to Vista later) you will have no problems with peripherals.
From your questions, I suspect that you have minimal computer knowledge, which makes you a juicy morsel for any clerk on a commission. The most important thing I can suggest is that you make friends with a geek. (Ask your friends. You have no idea how many of us are in the geek closet, and it's not gender specific.) Since real computer building nerds can't find an excuse to build more than one or so a year, they thirst for the challenge. Go getchyou one.
You haven't said, eithr what you need the computer for, so let's see what you would want at a minimum:
1) CPU: (the "chip" or heart of the computer. You don't really need Intel Core2Duo, if you want to save money, but they are nice. You can get an Athlon from AMD, as well. Lots of cheaper computers are getting rid of old generation chips like Celeron and PIV or lower. Don't get one of these. They won't be up to your needs in a year. Athlon, however, is just fine. I have one Core2Duo and one faster Athlon, and they are pretty much equal in my use (which is not overclocking, but something tells me that is now where you are at, anyway)
2) Hard Drive (SATA is the new standard, and I would go with that) at least 80GB. 140 better, but for the moment.
3) Memory: At least 1GB.
4) An operating system. You will want, if you don't go Mac (and they are pricey) either Windows XP(SP2) any version or Vista Home Premium or Ultimate. Do not go with Home Basic. Your system will probably offer Vista Home premium. If you happen to have a full XP installation disk, you don't need to buy another. If, however, it came from HP, it's oem (original equipment manufacturer) and Microsoft may not let you use it.
5) Video, CD/RW or other optical drive, Audio card, an ethernet port or card. All (or nearly all) computers have these. You'll be fine.
6) USB ports. The more the merrier. On front if possible.
7) Even though this is the last one you will need, sometimes a floppy drive is nice. If it doesn't have one, don't sweat it.
8) Cables. Do NOT buy them at a store. It's where they make their money. Some will come with the computer. Others go to the internet. Or Big Lots.
9) Peripherals. That's printer, Monitor, scanner, speakers, other stuff connected by a cable. Lots of these connect by USB these days.
Don't get suckered into buying these new if you already have them, unless there is one of those fabulous Dell deals with a free flat panel thrown in. You can get them later.
10) Software. What do you have? Make sure you have the install disks. You will need a productivity suite or at least a word processing program. The standard is Microsoft office or Microsoft Word these days. If it comes thrown in, fine. If not, you can buy an older version off the web fairly reasonably. Microsoft Works is not a viable replacement.
11) Protection: You MUST HAVE an Anti Virus program. All of the pre-built models come with bloat ware, which are really come ons for software which will cost you down the road. Don't fall for them. While you MUST have an updated anti virus program and an anti spy ware program, there are plenty of them for free on the web. A recent article here discussed some of the best.
12) Exotic ports, slots, slits, holes and other stuff and thingies: Card reader? Fire Wire? HDMI card? Surround Sound? Save that for the next one. If it's there, you may or may not use it. Don't let yourself get blinded by the frippery.