OK, this is taken from HTCs website:
3G - UMTS/ HSPA:
Europe/ Middle East/ Africa: 900/1900/2100 MHz with HSPA+ up to 42 Mbps <--- This is the EU handset, 801n (m7_ul)
Asia: 850/900/1900/2100 MHz with HSPA+ up to 42 Mbps <--- This is the Asian handset, 801s (m7_ul) (probably)
Canada/ Latin America: 850/1900/2100 MHz up to HSPA+ 42 Mbps <--- This is the North American GSM handset, 801n (m7_wlj or m7_wlv)
T-Mobile (US): 850/ AWS/1900/2100 MHz with HSPA+ up to 42 Mbps <--- This is the T- Mobile handset, 801n (m7_wlj or m7_wlv)
AT&T: 850/1900/2100 MHz with HSPA+ up to 21 Mbps <--- This is the AT&T handset, 801n (m7_wlj or m7_wlv))
Sprint: 1900/2100 MHz with HSPA+ up to 14.4 Mbps <--- This is the Sprint handset, 801c (m7_wls)
So, you check what 3G band you network uses and see which phones support it