The attachments are stored in a ftp server. This server could be anywhere. So as long as you don't modify ftp server I don't think that you'd have any problem with attachments.
If you move ftp server to another machine you should copy the excact tree to the new location.
And something I have notice when moving DB: If you export sd_userDB via backup from the current location and import it to the new location using restore sd_user (assuming that you use this db account) looses his rights and must be deleted and recreated using the old password... or I 'm doing something wrong since I'm not dba !