Okay, this is for everybody who wants to flash, so I don't have to keep typing it again and again:
TO BACKUP CONTACTS
1. Go to Contacts
2. Select "Options"
3. Mark ALL
4. Copy business Card "to Other Memory" i.e. your Memory Card (don't remove your memory card or format before flashing or anything, just don't do anything with it)
This way all your contacts will be saved. All you have to do after flashing is "Copy Contacts from Other Memory" back!
Regarding Messages, make sure all your messages are saved in your Memory Card. Simply select from "Options", "OTHER" and use "Memory Card". If you already are, you have nothing to think of.
Also, make sure you
UNINSTALL EVERY APP you have which is
Installed in your Memory Card, else their SPACE will be occupied for NO REASON.
TUTORIAL TO FLASHING: [Tutorial] How to flash with 3 files (C00, rofs2 and uda)
Recommended CFWs:
Shadow 1.5 CFW for 5530,5800,5233,5230,X6 based on C6v40 by Drigz [Updated]
.:InFinity-01:. - N97 Base - Nokia 523X - RM-625,588
Photon N97-01 - N97 FW Base - Nokia 5800,523x - RM-356,625,588 - Updated [26/06/2011]
Personally, I prefer the 2nd one, Infinity.
Your whole flashing process should take 2 minutes. Should you require any help, feel free to ask, before you flash.