I am also having a hard time installing Vista Ultimate x64 on my machine. I have the proper hardware yet in the middle of the installation it freezes or bluescreens. I will give you a more detailed report of what the BSOD stop code is if you need it. Here are my specs:

AMD Athlon 64 X2 6400+ Windsor 3.2GHz Socket AM2
ASUS M2N-SLI Deluxe AM2 NVIDIA nForce 570 SLI Mobo
G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400)
Western Digital Caviar SE16 WD5000AAKS 500GB 7200 RPM SATA 3.0Gb/s HDD
SAMSUNG 20X DVD±R DVD Burner SH-S203N
LITE-ON 20X DVD±R DVD Burner LH-20A1L-06

I feel like it might be a problem with my hardware because I couldn't get 64bit versions of Ubuntu or Xubutnu to install either. Any ideas would be greatly appreciated! Thanks.

Hello mattj.

Try removing 2GB of your RAM. There has been people that have had issues with installing with 4GB of RAM.

Unless you have Vista with SP-1 already in it that could be your problem.

hey mattj,
joel406 is right. i literally have the same exact machine you do. i built it 6 months ago and was having the same problem. It was because i was using 8GB ram when i was trying to install. I took 3 of my sticks out (6GB) leaving only a single 2GB stick in there and it worked fine. give that a try. good luck.

Thanks for the tips. I will give it a try and let you know. After installing did you put the rest of your RAM back in your machine without problems?

yup, after installation is successful just shut down, unplug the power, pop the rest of the ram back in and reboot. once rebooted make sure your system recognizes all of the ram. good luck.

Thank you 3 for your help. The install went perfectly well. I haven't popped my RAM back in but I don't see why that will be a problem. Thanks a ton for your help!

i have a gateway dx4200 amd phenom quad, Vista 64bit, w/ 6gb of ram, that I have reduced to 2gb (2 x 1gb) to avoid stop codes. I have not been able to reinstall extra ram (2 x 2gb). looking for answers for past 3 months when i have time...gateway support just wants to reinstall to as built -- f__ that. I think it must be a Microsoft Vista 64-bit problem, since so many different systems suffer from same problem.

I did end up putting my other 2GB back in but would get the same BSODs after about 10-15 minutes of up time. Any ideas? Again, I can check for stop codes if needed.

Use Memtest 86 ISO CD and test your RAM. Don't overclock until you are stable. Make sure your memory is identical.