HP Pavilion A6400F Desktop PC (2.2 GHz Intel Pentium Dual Core E2200 Processor, 3 GB RAM, 500 GB Hard Drive, DVD Drive, Vista Premium)

I had to send the first one back because it wouldn't start I got the replacement and it still wouldn't start up. I finally gave up and got my money back.

I purchased this HP Pavilion A6430F Desktop on May 30, 2008. I had gotten an HP all-in-one printer which was of such exceptional quality, I decided to make HP my next computer.
This computer worked fine for 6 months, and if I had written this review in the first month of ownership, I would have given it four or five stars.
However, after six months, it suddenly started to crash. I ran a diagnostics. It showed a hard drive and memory FAIL (Error code: biome-1/biohd-8) with a message instructing me to contact HP Support, but no contact information. I had to look up the customer support number online.
That call was a fiasco. I spoke to three people in the same department who each advised me they were connecting me to technical support. I told the third person that I had not reached technical support from the previous two transfers. He said, "Oh I will definitely not connect you to another customer support person." I proceeded to hold until the line was disconnected.
I turned the computer on again to see if there were anything I could do, but it now crashes on start-up.
After the no-support call, I did an online search for this machine and was astounded at the thousands of very negative reviews from people with exactly the same problems I have.
Save your money, avoid this product and, just to be safe, all other HP computer systems.

although the product is great I didn't know that it wouldn't operate a 64 bit system

This computer which I bought through Amazon freezes up for NO REASON it becomes completely useless and I have to pull the power cord to restart it. Amazon took it back for a full refund after HP was unable to fix it. I will never buy a HP system again but I love Amazon.

This computer is poorly built and does not function properly. My problem with this pc is a continuing failure of the video functions. It freezes up sometimes while other times it will display a "no signal imput" message on the screen. I have tried all the recommended procedures with no success and a lot of wasted time and effort. Trying to get assistance from HP on a warranty repair (you do all the work and maybe they'll send you a replacement part) is impossible.

My advice to you is do not buy HP desktops. I will never buy another HP product.