Lots of ways to share files without buying a new PC. Depends on if multiple people will be editing these files, or if they just need to be able to view them. Even with the Server, unless it's configured correctly, you could end up with two people editing the same file, and the last one to save wins.
You can use remote desktop to access files from home, one person at a time.
Any flavor of VNC can give access to files as well.
UltraVNC is my favorite, has a very user friendly FTP client built in to transfer files.
You can set up an FTP server.
Your ISP may provide an Online storage space. Comcast for instance provides 1 GB per email address on their home plan, and you can automatically upload files that have changed via FTP with a batch script.
You can use a free online storage site and upload files as they change, then those files can be accessed from anyplace. The free sites do have size limits.
To automatically upload files usually requires one of the paid plans. The free accounts are meant for personal home use; they may require a non-profit to use a business plan, but most of those are around $5 a month, a lot cheaper than a new PC.
Anyone with the account username and password can access the files, or they can be put into a public folder, or a shared folder that requires a link to get access. Mozy only allows 2 computers to access the Free Account
These come to mind:
Adrive - 50 GB, 2 GiB per file limit
DropBoks - 1 GB, 10 MiB per file limit
eSnips - 5 GB, 10 MiB file limit (50 MiB using their toolbar/uploader)
FileQube - 2 GB - link not responding right now
MediaMax Idrive - 2 GB, no limit, can be automated
Mozy - 2 GB, no file size limit, can be automated, 2 PCs max
Windows Live Skydrive - 25 GiB, 50 MiB per file limit
Idrive and Mozy are meant more as a backup service, so accessing the files form a different PC might not work, or may require a paid account.