I have a 64 bit machine from xi computers. http://www.xicomputer.com/ (tell 'em I sent you - they might send me a t-shirt or something ?) It's and Opteron 252 with JUST 4 gigs of ram. The motherboard will handle 24 gigs (when 4 gig sticks become available) I ordered mine with the nvidia 1400 graphics card. I downloaded the 64 bit version of Pro/E and it fired right up! No Problem. Is it fast - YES! Is it stronger - YES! Is it Better - YES! I put aside a Pent 4 3.2 ghz with 2 gigs ram and a Elsa Gloria III graphics card. This is a very nice machine, but no match for the Opteron. I am working with a HUGE and very complex assembly - effortlessly. I've added so much to this assembly in the past few days, I don't think the Pentium will pull it up. I love this thing, as you can tell - (wait for it) BUT, You will not find print drivers for it. HP does not support 64 bit computers. There are a FEW workarounds but not many. You will not be able to use "Add Printer" and catch a network printer. I was able to connect to and OLD 4V printer but my newer 800 plotter is not to be had. I have always printed to a file and copied the file to the plotter with a batch file, luckily that still works. Outlook will not work with more than 4 Gigs of ram until you call 1-800-MICROSOFT and ask for the patch. Yes, you have to ask for it, it's not available for download on their website! In short 64 bit is great, but there are quite a few drawbacks that must be culled out before it's acceptable.