Friend, this text is writen in a away that impossible to understand what you want. Perhaps your are still learning english, or did not put your ideas properlly. I sugest posting again, explaining 2 things: What you have and what you want to do. In addition, number your questions.
Have everything other than motherboard, CPU and PSU - if current 15" x 7.5" x 16" HP case is re-usuable. I suspect the in-hand HP case is considered micro ATX (the previous board was ~ 9.6"in × 9.6", but the previous PSU seems near full size ATX at 3.5"x 5.5"x 6"). If not, will need a standard case.
Looking for a reliable motherboard ("old" enough for a stable BIOS and drivers to already have been released) + an AMD or Intel CPU + a PSU. Use is for Office apps and Photoshop, and prefer stability over blazing speed. Integrated video is fine.
Have no idea where to begin, and suspect there are better combinations than the few "CPU+motherboard combos" offered on Newegg.
1) Is there a rational way to start to select and match up mobo+CPU combinations. Specific suggestions are very welcome.
2) Should any board labeled micro ATX fit the in-hand case (or even a mini-ITX in a subset of mounting holes)
3 Does a matching IO ports-backplate always come with a board?
4) Can current motherboards still boot into DOS?
5) Is PSU price generally related to reliability/quality or simply wattage (as it appears <= 400W are almost all <= $20 like the Diabloteks on Newegg.
6) Are the PSU mounting holes standard as long as the unit is about 6" across.
7) Is built-in PATA/IDE on the motherboard pretty much completely over?
8) If the HP case cannot be reused, any standard case will be fine.
Wish I could be more specific. But don't know quite how to start. Thanks for any and all comments.
I believe you can keep your case. Nevertheless, I would recomend getting a PC case that you LOVE, as this is an item that you will get once, and have it for the next 40 years. So if there is a specific one you really like, feel free to get it. It will always a good idea to get a full atx case. I like Bitfenix, they have full atx tower (Colossus), and an amazing ITX case (called Prodegy), and a lot of budget cases (Shinobi for example). I also like Moneual cases for HTPC style cases.
Your question is simple. Simply get an Ivy Bridge CPU and a mobo compatible, plus a good PSU. Im gonna recomend you to up your budget to $400. Perhaps get some parts now, and the last next month
The cheapest Ivy Bridge CPU, wich is alrady awesome is $200
A current Ivy Bridge mobo is around $100, but you can find great ones for less.
A Cooler Master Silent Pro 600W is around $100, less even, and I recomend it becaseu its totally silent.
1)As long as compatible, any mobo/cpu combination works perfect.
2)You have to check your case manual, but most cases fit all sizes of mobos
4)Im not sure but...probably yes and...certainly under windows.
5)It depends on build quality, like I said, the Silent Pro series is more expensive, but worth it. this is again, an item you will get once and have it for the next 10 years, so dont be cheap here.
7)Boards sitll have one IDE, for the optical drive, but can be used for HDD too.
8)Certainlly, again, check Bitfenix, Moneual, Raidmax, Cooler Master, Thermaltake...etc