Hi Benny,
I tried out the watercolor styles that use a gradient and they work fine with my machine that also has the Intel 82915G/GV/910GL graphics chipset. One thing you might want to try is to download the newest driver from the Intel website, since the one you're using is quite old. We actually blacklisted the below Intel driver versions, since we had too many problems with them (Impression won't be allowed to start up with those installed). It looks like we missed the one you have, which is 6.14.0010.3889
Blacklisted versions:
6.14.0010.3864, 6.14.0010.3865, 6.14.0010.3943, 6.14.0010.4543
The first one that works fine is: 6.14.0010.4704
The newest one from the Intel website is version 6.14.0010.4764, which also works fine.
Hope this helps,
Nikolai