Ive had my dual raptor raid 0 running for about a month now and have defragged twice using XP's built in one.
I've run sandra and ATTO, both are giving me scores about 80% of what I got before but I guess this is because I've now got the drives half filled - therefore I would say all is well with mine.
Sandra is giving me 59000 now, 69000 before. ATTO is giving me 80MB/s read/write now, 100MB/s before.
btw, I used 64k chunk size and 64 cluster size with NTFS. although this wastes a bit of drive space it should actually reduce fragmenting as fewer clusters are used.
<b>Vorsprung durch Dontwerk</b>.....<i>as they say at VIA</i>