It has become time to replace the antiques

As you may remember about 6 months ago my XP computer at my apartment died of a motherboard seizure the only parts still working are the three ATA hard drives.
and the ATA CD and DVD burners. Hope I can find a new system that will allow me to connect the ata drives as at least slaves since most of what I see out there have SATA support but no mention in the docs about ATA. But I was doing fine because I still had my Acer Aspire to get on line at my apartment. Nice little net book
As you know I have been finding odd errors with the mods I been testing on my relatives computer. I figured I was having either a memory error or video card issue. So I decided to run a memory diagnostic. It was then I discovered I could not enter the system bios to change the boot order so that I could run the mem test from my flash drive. I am almost never in the room when the computer boots up so did not notice it was not going through the normal POST where it lists the drives memory and such and allows you to press DEL to enter the bios or F2 to change the boot order. I figured reset the bios but wanted to make sure I was right so I spoke with two people who's technical advise I trust more than my own.
They suggested the same So I looked for the bios reset jumper and of course there was not on. So I unplugged the computer, Removed the battery, ate dinner,
replaced the battery, plugged the computer back in pressed the start button and it now does nothing except spin up the hard drive, blink the cd light and floppy disk lite, yes it has a floppy drive all my computer do. So what if I am old school. Anyway it is now time for two new computers. I can not afford a lot of money but I do want a good system that will
A: allow me to hook up my ATA hard drives (not via USB but a Motherboard ATA connector.
B: allow me to set up a duel boot system so that I can access either the XP OS or the Windows 7 OS. NO I WILL NOT USE WINDOWS 8 it is too dam new. I am loath to even consider using windows 7 but with Microsoft Ending support for XP I have little choice.

In the past I have built from scratch every computer I have ever owned. I have never purchased a computer off the shelf so to speak. I will not purchase a computer over the Internet either. I must Touch it and see inside the case prior to paying for it. I would not want something that I could not upgrade or tweak on. Also it must be a Desk Top because I want everything inside and not hanging off USB cables and sitting all over my desk.

Hey just wondering do computers these days have parallel ports, and PS2 connectors for Keyboards. You do not know what a PS2 connector is it is a round connector with 6 pins. If they do not my custom keyboards may not function. I know they make PS2 to USB adapters or at least they did. But as some of you are aware my left arm and hand have some sever limitations. So my keyboards are unique.

Anyway to much rambling.