HP HP Compaq

Hello
My company is preparing to replace all our Dell SX270
SmallFormFactors.
Because we use HP Proliant Servers I thought it would be a good idea
to replace the
Dell’s with HP UltraSlim and/or SFF. Thus I started to look at current
models, used models, refurbished models to get a feel on what HP
offered new and old.

I ended up reasonably confused. I have HP, HP Compaq, Proliant,
Pavillion and so forth.
To list a few I have HP DC7800, DC7900, HP 6200, HP Compaq 8200-8300
Elite, HP z220, HP Compaq 4000 and so forth. At least with Dell one
can buy a SFF in one purchase area. With Hp the sales are generously
scattered from one HP site to another HP site.

I have no idea is HP and HP Compaq is one company?
What I need to know so I can present to management should we consider
buying be it used, refurbished, new for our business workstations HP
or HP Compaq. I have studied the specs on all models and I see the
progressive evolution. Xp to Vista to Windows 7 32 bit to 64 bit. The
intel core, memory, sata drives. Let me know your thoughts. Thanks