Buzz Out Loud Lounge: Highly Technical Problem

Highly Technical Problem

Ok, first lets get the mandatory stuff out of the way, i've listened to BoL for a good 400 episodes now, and dont miss a single one! second, its a tech podcast, and i need a tech answer so i thought this would be as good a place as any to ask.

Technical bit coming up.

Ok, i've been running Windows XP x64 for about 2 years now, and while its certainly not a choice for everyone, i'am thoroughly happy with my choice of OS, however, after upgrading my PC a little at christmas, i've noticed a drop in Audio quality being produced from my PC, especially in games. Now, i upgraded my Graphics card from a 7900GTX, to a 8800 GT, at the same time i bought another 2GB of ram, to take me upto 4GB in total. Now, even though Windows XP x64 (as do all x64 OS's and those that are also Large Address Aware) natively supports >4GB of RAM, a Bios switch needs to be enabled for the Bios to report >3GB to the OS (Memory Remapping). Now, the trouble i seem to have noticed, and after as much reading as i could find on the subject it has come to my attention, that, with the Memory Remapping Feature enabled, all memory between 3GB and 4GB in the virtual adressing space is remapped above 7GB in the address spacing, this however (even with x64 drivers) stops most 32bit compliant PCi devices to allocate buffered memory in RAM, this has lead to my noticing that while the 'Memory Remapping' feature is turned on, i get all 4095 (yes, minus 1mb) of my system memory BUT i lose 'ALL' hardware mixing options (D3D Sound/OpenAL) on both of my sound cards, if i turn 'Memory Remapping' off, Windows only see's 3008 (2.93GB) Megabytes of RAM, and 'ALL' hardware mixing options are re-enabled.

Now, my question is, given that this is obviously a hardware issue (something possibly to do with PCi only supporting 32bits on its Frame buffer, but this may or may not be wrong of course), would either of the following 2 suggestions fix this problem ?

Suggestion 1: Instal and run Windows Vista x64. With the changes to the DirectSound management sub systems in Vista, would this change the way resources are allocated to the PCi frame buffer and allow the use of both Memory Remapping and Hardware sound mixing ?

Suggestion 2: Instal a Creative (or indeed Asus) PCi-E sound card, with the hope that the using a PCi-E interface negates this error.

Any help is greatly appreciated, and if there is any extra information you need, dont hesitate to ask.

~Linear.CannoN