Vista is excellent for a the following: an HTPC or 64bit. xp64 is horrid no matter how bad people make Vista out to be it's light years superior to xp64, if you want 64bit Vista is it (or was until 7). And no opensource HTPC frontend was as polished IMO as Vista Media Centre. And trust me I tried 3 or 4 of the most popular xp frontends out there. You could use XP media Centre edition but that's also only 32 bit as well. Why do you want to run 64 bit on 512 Ram (and on top of that a Celeron m)? It defeats the entire purpose of the main reason 64 bit is in fashion - it allows you to use more RAM by getting past the 4gb limitation on 32bit systems. More RAM better performance
The read/write cycles of desktop RAM is far more intensive than what a USB stick is designed for. Not only is it slower but expect to have a shortened lifespan. Read this.
http://www.pcstats.com/articleview.c...id=2160&page=5 The effects of readyboost are marginal for underpowered systems. Notice now 1gb of system ram is outperforming 512mbs +4gb of Readyboost in most applications? What you're trying to do is the equivalent of trying to push a 10 ton truck up Mount Everest using a wheelbarrow. Stick with 32bit xp, buy a 512mb stick of Sodimm DDR Laptop Ram which costs peanuts now for real improvement