Hi Poincare, I hate to tell you this, but Vista x86 Sp 1 does show whatever total ram insalled there is, but it still does not use more than 3,3 gb because of the address limit with 32 bit number. That's it. It'll show you have 8 gb but will be actually using only 3,3.
Choose which is more importat to you, and then choose it x 64 or x 86. Writing your hardware manufacture asking for x 64 drivers could help in time. Perhaps using 2 OS's x 64 and x 86 for different needs could be your practice for a while.