FWIW - Have been having some problems with a Dell Optiplex 745. Plugged in the USB disk which had the most recent image on it, told Acronis to Restore - and did just what was written on the box (and in less time than it took to create the image in the first place).
Switched system off and re-started - and there everything was.
Impressive - first time I've actually had to do a recovery for real.
Now - admit this doesn't quite answer the question asked (80Gb to 160Gb hard disks). But it could be worthwhile just to try and see what happens.
From the manual, it certainly looks as though what you want is possible. From the manual:
6.3.7 Changing the restored partition file system
Though seldom required, you can change the partition file system during its restoration.
Acronis True Image Home can make the following file system conversions: FAT 16 -> FAT
32, Ext2 -> Ext3. For partitions with other native file systems this option is not available.
Let’s say you want to restore a partition from an old, low-capacity FAT16 disk to a newer
disk. FAT16 would not be effective and might not even be available for the high-capacity
hard disk. That's because FAT16 supports partitions up to 4GB, so you will not be able to
restore a 4GB FAT16 partition to a partition that exceeds that limit without changing the file
system. It would make sense here to change the file system from FAT16 to FAT32.
However, keep in mind that not all operating systems support FAT32. MS-DOS, Windows 95
and Windows NT 3.x, 4.x do not support it and will not be operable after you restore a
partition and change its file system. These can be normally restored on a FAT16 partition
only.
6.3.8 Changing the restored partition size and location
You can resize and relocate a partition by dragging it or its borders with a mouse on the
horizontal bar on the screen or by entering corresponding values into the appropriate fields.
Using this feature, you can redistribute the disk space among partitions being restored. In
this case, you will have to restore the partition to be reduced first.
These changes might be useful if you are to copy your hard disk to a new high-capacity one
by creating its image and restoring it to a new disk with larger partitions.
If you need any more information, drop me a PM. I rather think you can actually download the entire Acronis manual from their web site.
Good Luck!