Out of the box, your Samsung i8510 can't download maps from Route66's (Samsung Navigator's) online store... here's how you fix the problem:

1) Connect the phone to your PC and select Mass Storage mode (or use Y-Browser if you're familiar with it)
2) Navigate to the E:\System folder on your PC (where E: is the phone's internal mass storage, NOT a memory card)
3) Create the following folders (each is a sub-folder of the one above):
3.1) Apps
3.2) Route66_V8
3.3) Data
3.4) Maps
4) Check you now have E:\System\Apps\Route66_V8\Data\Maps as a folder path
5) Disconnect the phone from the PC (to give the phone access to it's E: drive again)
6) Go into Route66 > Extras > Maps > Route 66 store and see if it will now let you download maps to your phone :)

To get voices to work (your phone has one voice pre-installed, but in the wrong place) you need to do the following:

1) Download Y-Browser from http://www.drjukka.com/YBrowser.html
2) Install Y-Browser onto your phone
3) Open Y-Browser and navigate to Z:\System\Apps\Route66_V8\data\audio
4) Copy the english-female.speech file there (press options > edit > copy)
5) Navigate to E:\System\Apps\Route66_v8\data\audio
6) Press Options > edit > paste to copy the file into this location

*that should be it, but to be sure, there's another file worth copying*

7) Navigate to Z:\System\Apps\Route66_v8\data\StringRes
8) Copy the 01 - english.lang file in there (press options > edit > copy)
9) Navigate to E:\System\Apps\Route66_v8\data\StringRes
10) Paste this file into that location (press Options > Edit > Paste). IF Y-Browser pastes both files into this location, highlight the english-feemale.speech file and press the C key to delete it

That's everything - in Route 66 you'll now have English Female as an available voice.