MemoryError in band function WriteRaster

[jorgearevalo]

I'm getting a memory error in python binding:

Traceback (most recent call last):
  ...
  File "/usr/lib/python2.6/dist-packages/osgeo/gdal.py", line 859, in WriteArray
    return gdalnumeric.BandWriteArray( self, array, xoff, yoff )
  File "/usr/lib/python2.6/dist-packages/osgeo/gdal_array.py", line 167, in BandWriteArray
    array.tostring(), xsize, ysize, datatype )
MemoryError

With GDAL 1.6.3, Python 2.6

I was creating a big blank raster (about 5000x5000 pixels), to apply gdal_rasterize over it. I know since GDAL 1.8.0 gdal_rasterize creates the raster dataset, but I can't use it.