Below is a section from the log. The drive has about 12GB free. 
The preferences are set to the default, which is "Use at most 10 GB". 
I upgraded because I wanted to try Cuda.

4/6/2009 6:16:51 PM|SETI@home|Sending scheduler request: To fetch work.  Requesting 60480 seconds of
work, reporting 0 completed tasks
4/6/2009 6:16:56 PM|SETI@home|Scheduler request completed: got 0 new tasks
4/6/2009 6:16:56 PM|SETI@home|Message from server: No work sent
4/6/2009 6:16:56 PM|SETI@home|Message from server: Astropulse v5 needs 60.00MB more disk space.  You
currently have 0.00 MB available and it needs 60.00 MB.
4/6/2009 6:16:56 PM|SETI@home|Message from server: SETI@home Enhanced needs 32.00MB more disk space.
You currently have 0.00 MB available and it needs 32.00 MB.
4/6/2009 6:17:56 PM|SETI@home|Sending scheduler request: To fetch work.  Requesting 60480 seconds of
work, reporting 0 completed tasks
4/6/2009 6:18:06 PM|SETI@home|Scheduler request completed: got 0 new tasks
4/6/2009 6:18:06 PM|SETI@home|Message from server: No work sent
4/6/2009 6:18:06 PM|SETI@home|Message from server: Astropulse v5 needs 60.00MB more disk space.  You
currently have 0.00 MB available and it needs 60.00 MB.
4/6/2009 6:18:06 PM|SETI@home|Message from server: SETI@home Enhanced needs 32.00MB more disk space.
You currently have 0.00 MB available and it needs 32.00 MB.
4/6/2009 6:19:54 PM||No general preferences found - using BOINC defaults
4/6/2009 6:19:54 PM||Reading preferences override file
4/6/2009 6:19:54 PM||Preferences limit memory usage when active to 1023.21MB
4/6/2009 6:19:54 PM||Preferences limit memory usage when idle to 1841.78MB
4/6/2009 6:19:55 PM||Preferences limit disk usage to 10.00GB
4/6/2009 6:20:19 PM||No general preferences found - using BOINC defaults
4/6/2009 6:20:19 PM||Reading preferences override file
4/6/2009 6:20:19 PM||Preferences limit memory usage when active to 1023.21MB
4/6/2009 6:20:19 PM||Preferences limit memory usage when idle to 1841.78MB
4/6/2009 6:20:19 PM||Preferences limit disk usage to 100.00GB
4/6/2009 6:20:22 PM|SETI@home|Sending scheduler request: To fetch work.  Requesting 60480 seconds of
work, reporting 0 completed tasks
4/6/2009 6:20:32 PM|SETI@home|Scheduler request completed: got 0 new tasks
4/6/2009 6:20:32 PM|SETI@home|Message from server: No work sent
4/6/2009 6:20:32 PM|SETI@home|Message from server: Astropulse v5 needs 60.00MB more disk space.  You
currently have 0.00 MB available and it needs 60.00 MB.
4/6/2009 6:20:32 PM|SETI@home|Message from server: SETI@home Enhanced needs 32.00MB more disk space.
You currently have 0.00 MB available and it needs 32.00 MB.