Need help grouping multiple rows into single string based on GROUP BY?

This question may have been asked before but I've been doing some digging and can't find anything quite like it. Thanks in advance

EDIT: Totally forgot. We're using SQL 2005 (otherwise I'd likely just use GROUP_CONCAT)

Sample Table:

ID  CATEGORY    ATTRIBUTE
1   A   Piano
1   A   Saxophone
1   B   Jazz
1   C   Mellow
1   C   Pensive
2   A   Drums
2   A   Guitar
2   B   Rock
2   B   Classics
2   C   Upbeat
2   C   High Energy

Desired Output:

ID  CATEGORY    ATTRIBUTE
1   A   Piano, Saxophone
1   B   Jazz
1   C   Mellow, Pensive
2   A   Drums, Guitar
2   B   Rock, Classics
2   C   Upbeat, High Energy