I have recently built a new PC, and following comments made by Tomasz within the last few months went with XP Pro x64 as my operating system. I upgraded to Amibroker Pro and installed both 64 and 32 bit versions. Initially I wondered if I had mucked up my install, as both versions seemed equally fast. I then loaded in a more demanding scan. The first run is limited by how quickly the history loads off the HDD. After that, the 64 bit version really flies. For example, one scan on the full US database dropped from 120 seconds to 54 seconds running x64. (both on the same machine).
Almost everything else works too, although if your other hardware is old you may have problems. My Epson printer still works, but the 64 bit driver is only a close fit, and doesn't show status of the ink cartridges. All in all I'm pleased with my choice, so thank you Tomasz for good advice. I had bought Neospeech voices for my previous machine, and the "say" feature is just so much better once you get rid of MS "Sam". Getting "Kate" to run just wasn't happening on x64 Amibroker. The supplier couldn't help and advised checking with Amibroker. Needless to say its nothing to do with Amibroker, but Tomasz gave me a concise technical explanation why this was so, much better than I had found after trying Google and the voice supplier. I disappeared for Christmas holidays before I had a chance to thank Tomasz, so would like him to know his response really was appreciated.
