I agree with Clevo. See the information from the link given below, in particular the 'Recommended system requirements'. Where it says '40 GB hard drive...', that also implies a partition size on a larger hard drive should you choose to use one. When you install Vista, the complete disk image is stored on your hard disk and is then expanded. The hard disk, or partition, therefore needs to be large enough to hold BOTH the disk image AND the expanded version as well as having a minimum of working space available for the system to use when expanding the files. With modern disk filing systems such as NTFS, there isn't as much need for disk partitioning on modern machines. This was often used on older machines because back then hard drives were more expensive and it was in everyones interest to ensure that storage space was used as efficiently as possible. Disk drives are divided into sectors, with groups of these sectors forming a single storage unit called a cluster. Each individual file, whether it be a few bytes or several megabytes in size, occupies at least 1 cluster. Because of the address capacity limitation of older filing systems, the larger the disk capacity the larger the clusters and the more space wasted. This was partially overcome by dividing the drive into smaller partitions. The filing system on Vista, NTFS, does not suffer from this limitation.
Dwarf Windows Vista Ultimate
Footnote: These are the recommended requirements for the Ultimate edition of Vista, but looking at the Home Premium edition (which is what you have), the requirements are identical.