Windows above 4GB RAM

[vich]

I found an EBAY PC that offers 8GB RAM here (http://cgi.ebay.com/IBM-IntelliStation-A-Pro-2-2-2GHz-Wildcat-Realizm-800_W0QQitemZ120137266831QQihZ002QQcategoryZ140072 QQcmdZViewItem).

It runs Windows XP Pro. So; does Windows XP Pro utilize anything above 4GB? It doesn't explicitly state XP 64, but maybe that could be assumed.

For 64bit: I've heard about hardware compatibility but besides my printer (that I don't mind replacing), I wouldn't expect to add hardware other than perhaps a new SATA or SCSI hard disk.

However; for 64 bit OS, should I be concerned with application compatibility? I mainly run the Adobe CS2 Suite (Photoshop, Lightroom, Bridge, etc) and other imaging software. I could live without the other stuff, but if I bought a PC that didn't work with Lightroom 1.1 and Photoshop CS2 (and CS3 soon) then it would not be of use.

I also, of course, run Microsoft Office.

Thanks in advance.

[Puter Padowan]

XP Pro 32 will only work with 4 GB of RAM. The 64 bit version supports up to 128MB RAM.

There are currently not many programs that will run on a 64 bit OS. The only thing I DO know is M$ is working on Office 2007 which WILL run but with limited capabilities. I don't know what "limited" means though. Previous versions of office will not run on a 64bit OS.

[Paul Komski]

There is supposed to be much 32-bit compatibility under the WOW subsystem for programs but not for hardware drivers or 16-bit apps.

http://support.microsoft.com/kb/896456


And

64-bit systems sometimes lack equivalents to software that is written for 32-bit architectures. The most severe problem is incompatible device drivers. Although most software can run in a 32-bit compatibility mode (also known as an emulation mode, e.g. Microsoft WoW64 Technology), it is usually impossible to run a driver (or similar software) in that mode since such a program usually runs in between the OS and the hardware, where direct emulation cannot be employed.

http://en.wikipedia.org/wiki/64-bit

[vich]

Thank you for the responses.

OK, can I (I assume I can) install a dual boot for Win 32 so if I'm stuck on some critical software some day I can just reboot? Obviously; I'll need to aquire an XP Pro 32 license.

As mentioned, I use Adobe Photoshop CS2. Here's their article (http://kb.adobe.com/selfservice/viewContent.do?externalId=320005)stating that it works, but that it is a 32 bit application. However; using the 64 bit OS permits more memory usage (if I have 4GB or more on the computer ... I will have 5GB).

Their engineer blog here (http://blogs.adobe.com/scottbyer/2006/12/64_bitswhen.html), a bit more informative.

Bottom line is; 64 bit OS will work in WOW64 (32 bit emulation) but necessary things like my $300 Monitor Color Calibration software won't be supported.

The extra memory usage (above the 1.7GB for Photoshop limit) is broken and that's saying something, but not at the expense us missing necessary device drivers.

So then, it sounds like I'll be doing a dual boot into XP Pro 32.

[vich]

I wanted to quote a particularly relevant response in that blog (http://blogs.adobe.com/scottbyer/2006/12/64_bitswhen.html)- sort of exactly what I was looking for, albeit this was from May and I'm thinking 2 months is a lot of time for driver manufacturers to catch up more:
[Yes, I believe you might have missed something. Adobe Photoshop being a 32-bit application does not prevent you from moving to 64-bit hardware running a 64-bit version of Windows. Photoshop CS2 and Photoshop CS3 run just fine on Window XP and Vista 64-bit versions (yes, I know the support page says it's certified only on the 32-bit versions, but I personally worked on Windows XP 64-bit edition for part of the Photoshop CS2 and all of the Photoshop CS3 cycle). In fact, they recognize when a machine has a very large amount of memory available and tweak how some operations are done to both use more address space directly (4GB instead of 2GB), and to let the operating system use memory beyond our address space on our behalf. And in the 64-bit version of Vista, the size of that cache is essentially unlimited, meaning that there are performance gains in having more than 6GB RAM in a machine - I've had Vista essentially using ~10GB on Photoshop's behalf on a machine with 16GB in it. This, and other reasons, are why a fully 64-bit version of Photoshop may not end up with any performance benefit at all over the 32-bit version. The only things that absolutely have to be 64-bit when you wan to move to a 64-bit version of Windows are drivers - so I don't think Photoshop remaining 32-bit should stop you from moving. - Scott]

XP Pro 32 will only work with 4 GB of RAM. The 64 bit version supports up to 128MB RAM.

There are currently not many programs that will run on a 64 bit OS. The only thing I DO know is M$ is working on Office 2007 which WILL run but with limited capabilities. I don't know what "limited" means though. Previous versions of office will not run on a 64bit OS.
Puter: Do you mean "will not work" or "will not take advantage of 64 bit addressing"? Obviously; I got the answer for Photoshop (and hopefully Bridge and Lightroom), but can I assume that most mainstream applications will run on XP Pro 64 or not? Thank you.