Perhaps I have missed it but has anyone suggested the old SPSS command "Sample"?  Here is info from the SPSS v18
 syntax reference:
SAMPLE
SAMPLE {decimal value} or {n FROM m }
 This command does not read the active dataset. It is stored, pending execution with the next command that reads the dataset. For more information, see the topic Command Order on p. 40.
 Example
SAMPLE .25.
 Overview
SAMPLE permanently draws a random sample of cases for processing in all subsequent procedures.
 For a temporary sample, use a TEMPORARY command before SAMPLE.
 Basic Specification
 The basic specification is either a decimal value between 0 and 1 or the sample size followed by keyword FROM and the size of the active dataset.
- To select an approximate percentage of cases, specify a decimal value between 0 and 1.
- To select an exact-size random sample, specify a positive integer that is less than the file size, and follow it with keyword FROM and the file size.
 
 Operations
- SAMPLE is a permanent transformation.
- Sampling is based on a pseudo-random-number generator that depends on a seed value that is established by the program. On some implementations of the program, this number defaults to a fixed integer, and a SAMPLE command that specifies n FROM m will generate the identical sample whenever a session is rerun. To generate a different sample each time, use the SET command to reset SEED to a different value for each session. See the SET command for more information.
 
 So, I think something like:
 Temporary.
Sample 100 from 1000.
 save outfile= etc.
 Probably embed it in a loop or other structure to generate as many samples as one wants (probably create a new variable
 ranging from 1 to 100 in all files which would allow one to use Match files to combine them all into a single file). Or something like that.
Mike Palij